More Email Shenanigans

Question

I don't know how these people know my email address, but after the (still unsolved) shenanigans of the Interesting email I received? I got... yet another email. This one was of a Google Drive document that had been shared with me to comment on; I'm going to link it here in case anyone can find out what to do with it.

https://docs.google.com/document/d/1mwiVJlB9rlSbRmXpvOtWO0objtz7IQR75_seg429HmY/edit

If you want the diamond with the letters enlarged, I've got a separate doc with it enlarged here:

https://docs.google.com/document/d/1oZs8GsnPtU7ePAz-MJHkgpsb991JYYxzcIS-QrKFveQ/edit

I really hope this stops or something comes of it.

As always, partials are welcome, and good luck.

Answer 1

Some partial progress

The grid is

four separate multiplication tables, base 10, 16, 6, and 9.

The numbers below the grid

spell out "You should check this document on a regular basis" with 1=A, 2=B, etc. (hinted by A1Z26 on the second page).

Treating the colored numbers

as numbers in the corresponding base and doing the corresponding arithmetic, we get:
1 (black, left). 10
4 (black, left). 9
3 (red, right). 17 (or 11 base 16)
2 (blue, left). 5 (or 5 base 9)
5 (green, right). 19 (or 31 base 6)
6 (black, left). 80