[Map] Fire Red: AdvancedMap is probably messing up behavior and background bytes

[Entaro Ceraphenine]

Hello!
I had changed several blocks from Viridian City's tileset with tiles from Emerald. I did not directly port it, I manually made blocks and tiles and palettes from scratch. When I first first the new tiles, everything seemed normal. But after I changed the amount of blocks to 384, all the behavior bytes and background bytes have these weird random numbers:
https://imgur.com/a/A4KokTw
These were not here the first time and now there are these random numbers in every blocks of this tileset. And as such, some blocks don't behave the intended way. Is it safe to change these behavior bytes and background bytes to the values I want them to? And for that matter, I have a couple of other questions as well:

First of all, if I change the amount of blocks, does Advanced Map automatically repoint data to some other place (cuz more blocks should need more spaces, right)? Or does it overwrite existing bytes? If it is the later, than how can I be sure that it is not overwriting something important? In such a case, will continuing to edit the tileset data be safe at all?

There is this another issue: I tried using the triple layer blocks by Sierraffinity but it did not work. Rather, after applying the hack, some blocks appeared minorly glitchy. Nothing game breaking but weird like this: https://imgur.com/a/PH62sHl
This made me somewhat sure that A-Map is messing with existing data. How do I go around this one?

Thanks in Advanced!