_{Partial answer - core of the puzzle uncovered but step to final answer missing...}

Several of the flags (marked below in round brackets) have red sections instead of yellow; others {curly brackets} have black sections which should be white. If we fix these, then we produce the message:
(D)(E)BUSSYS  {C}UAIRE (D)(E)  (B){(L)}ANK

This message itself contains a further mistake - the second 'U' should be an 'L' to spell out "DEBUSSY'S CLAIRE DE BLANK", the answer to which is LUNE (completing the title of one his well known pieces of music).

Two Braille letters here are corrupted, but the overall message appears that it should spell out "ELEMENT (N)INETY (T)WO", the answer to which is URANIUM (symbol 'U'), after consulting the Periodic Table.

This Pigpen cipher contains several completely superfluous letters:
F(M)RENC(D)H W(V)OR(B)D F(M)O(P)R K(H)ING(U)S

This appears to give us the message "FRENCH WORD FOR KINGS", the answer to which is ROIS.

The semaphore message also contains several mistakes, coming out as:
N{NN}MBER AF(B)TER T{QY}REE

Here it appears we should substitute a 'U' for the first NN, remove the B, and sub in an H for the QY to read the message "NUMBER AFTER THREE", the answer to which is FOUR or 4 if dealing with integers.

The Morse code translates to:
PROTEI(A) HAVIN(W) (N) FAMOUSL(Q) LON(W) NAME

This appears like it should read (with substitutions) as "PROTEIN HAVING A FAMOUSLY LONG NAME", the answer to which is TITIN (see this link, for example).

LUNE + U(RANIUM) + ROIS + FOUR + TITIN

But I cannot yet see what we are expected to achieve with this, the significance of the deliberate mistakes, or how the title relates to the puzzle itself... Further thought required...

_{Partial answer - core of the puzzle uncovered but step to final answer missing... (see @Zimonze's answer for that)}

Several of the flags (marked below in round brackets) have red where yellow should be, or vice versa, while others {curly brackets} have black where white should be, or vice versa. If we fix these, then we produce the message:
(D)(E)BUSSYS{C}{(L)}AIRE(D)(E)(B){(L)}ANK

Note that with added spaces this message spells out "DEBUSSY'S CLAIRE DE BLANK", the answer to which is LUNE (completing the title of one his well known pieces of music). Note also that all of the corrupted flags occupy the first two letters of each word in the message.

Three Braille letters here are corrupted, but the overall message appears that it should spell out "(E)LEMENT (N)INETY (T)WO", the answer to which is URANIUM after consulting the Periodic Table. Note also that the corrupted letters occupy the first letter position in each word in the message.

This Pigpen cipher contains several completely superfluous letters:
F(M)RENC(D)H W(V)OR(B)D F(M)O(P)R K(H)ING(U)S

This appears to give us the message "FRENCH WORD FOR KINGS", the answer to which is ROIS. Note also that the superfluous letters have been inserted at the second and second-to-last letter positions in each word.

The semaphore message also contains several mistakes, coming out as:
N{NN}MBER AF(B)TER T{QY}REE

Here it appears we should substitute a 'U' for the first NN, remove the B, and sub in an H for the QY to read the message "NUMBER AFTER THREE", the answer to which is FOUR. It appears that the second letter in each word of the message is replaced by 2 others (if you consider an F to FB replacement in the second word).

The Morse code translates to:
PROTEI(A) HAVIN(W) (N) FAMOUSL(Q) LON(W) NAME

This appears like it should read (with substitutions) as "PROTEIN HAVING A FAMOUSLY LONG NAME", the answer to which is TITIN (see this link, for example). Note that in each of these cases the last letter of each word has had its Morse configuration reversed, even the last one where the reverse of E (a single dot) is itself!

LUNE, URANIUM, ROIS, FOUR, TITIN

At this point I had to go to bed, and had not quite pinpointed the patterns to the corrupted letters (thanks to @Jens and @athin for their comments overnight) and so did not appreciate how to define their derivation and figure what was required next. In the meantime the remainder of the puzzle was solved by @Zimonze - so now go read their answer after this one to finish the story!

Partial answer

There are 5 messages encoded in the image, respectively in:

International Maritime Signal Flags, Braille, Pigpen cipher, Semaphore, and Morse code.

However:

Each message has several mistakes within it...

Message 1:

Several of the flags (marked below in brackets) have red sections instead of yellow; others have black sections which should be white. If we fix these, then we produce the message:
(D)(E)BUSSYS {C}UAIRE (D)(E) (B){L}ANK
Round brackets indicate red for yellow, curly brackets indicate black for white in addition.

This message itself contains a further mistake - the second 'U' should be an 'L' to spell out "DEBUSSY'S CLAIRE DE BLANK", the answer to which is LUNE.

Message 2:

Two Braille letters here are corrupted, but the overall message appears that it should spell out "ELEMENT (N)INETY (T)WO", the answer to which is URANIUM (symbol 'U').

Message 3:

This Pigpen cipher contains several completely superflous letters:
F(M)RENC(D)H W(V)OR(B)D F(M)O(P)R K(H)ING(U)S

This appears to give us the message "FRENCH WORD FOR KINGS", the answer to which is ROIS.

Message 4:

The semaphore message also contains several mistakes, coming out as:
N{NN}MBER AF(B)TER T{QY}REE

Here it appears we should substitute a 'U' for the first NN, remove the B, and sub in an H for the QY to read the message "NUMBER AFTER THREE", the answer to which is FOUR or 4 if dealing with integers.

Message 5:

The Morse code translates to: PROTEI(A) HAVIN(W) (N) FAMOUSL(Q) LON(W) NAME, which appears like it should read (with substitutions) as "PROTEIN HAVING A FAMOUSLY LONG NAME", the answer to which is TITIN (see this link, for example).

Altogether then we appear to have:

LUNE U(RANIUM) ROIS FOUR TITIN

But I cannot yet see what we are expected to achieve with this, or how the title relates to the puzzle itself... Further thought required...

_{Partial answer - core of the puzzle uncovered but step to final answer missing...}

There are 5 messages encoded in the image, respectively in:

International Maritime Signal Flags, Braille, Pigpen cipher, Semaphore, and Morse code.

However:

Each message has several seemingly deliberate mistakes within it...

Message 1:

Several of the flags (marked below in round brackets) have red sections instead of yellow; others {curly brackets} have black sections which should be white. If we fix these, then we produce the message:
(D)(E)BUSSYS {C}UAIRE (D)(E) (B){(L)}ANK

This message itself contains a further mistake - the second 'U' should be an 'L' to spell out "DEBUSSY'S CLAIRE DE BLANK", the answer to which is LUNE (completing the title of one his well known pieces of music).

Message 2:

Two Braille letters here are corrupted, but the overall message appears that it should spell out "ELEMENT (N)INETY (T)WO", the answer to which is URANIUM (symbol 'U'), after consulting the Periodic Table.

Message 3:

This Pigpen cipher contains several completely superfluous letters:
F(M)RENC(D)H W(V)OR(B)D F(M)O(P)R K(H)ING(U)S

This appears to give us the message "FRENCH WORD FOR KINGS", the answer to which is ROIS.

Message 4:

The semaphore message also contains several mistakes, coming out as:
N{NN}MBER AF(B)TER T{QY}REE

Here it appears we should substitute a 'U' for the first NN, remove the B, and sub in an H for the QY to read the message "NUMBER AFTER THREE", the answer to which is FOUR or 4 if dealing with integers.

Message 5:

The Morse code translates to:
PROTEI(A) HAVIN(W) (N) FAMOUSL(Q) LON(W) NAME

This appears like it should read (with substitutions) as "PROTEIN HAVING A FAMOUSLY LONG NAME", the answer to which is TITIN (see this link, for example).

Altogether then we appear to have:

LUNE + U(RANIUM) + ROIS + FOUR + TITIN

But I cannot yet see what we are expected to achieve with this, the significance of the deliberate mistakes, or how the title relates to the puzzle itself... Further thought required...