So there are certain glitchy areas or "corrupted" zones, where the player is instantly killed when they approach. These zones are commonly surrounded by walls in the ruins generated by this mod. Are these intended traps, in addition to having some be guarded by turrets, or is something broken?

Big mods in my current list include bobs, angels, omnimatter, yuoki, natural evolution, bullet trails, endgame combat, alien biomes, and geothermal. The reason I mention most of these mods should be obvious, but for alien biomes and geothermal, the problem often happened in a volcano biome, where geothermal wells frequently spawn. I doubt they are related to the problem, since I have not extensively tested, but I include them just in case.

EDIT: These glitchy areas seem to be some kind of explosive? Walking into it causes an explosion which is instant death for a new character, but placing a wall in the vicinity also triggers the explosion, with a good range. However, placing at max vanilla distance (6 units away) can trigger the explosion without killing the player. The dangerous zone is then permanently removed. Simply respawning after being killed did not remove the corrupted zone, of course. Extremely weird, but at least I don't have to worry about these corrupted areas when expanding the base!

I do believe they are landmines, get some shield and you can survive

Yep, landmines, as I warn about in the description of the mod. Gotta be careful! A player with decent armor should be able to survive one.

Hmmm, I don't see anything in the description about landmines, either invisible or otherwise.. hopefully their invisibility in my game is just caused by other mods in my current modpack, because there's no way you intended to have invisible landmines guarding these ruins, right? O_o

Enemy mines are invisible.I build a mine on the ground and select it with creative mod wand and turn it into an enemy mine.Then it becomes invisible.
A full HP player with a light armor will barely survive one and have little HP left.