Has anyone figured out the purpose of these records? They are obviously some sort of categories but I haven't figured out any practical use outside keeping record of specific mods.

Well I assume modcol is short for mod collection, I noticed it's used on weapons for combination naming for simple random and epic.

Yes yes.. of course. FO4Edit doesn't list any reference for modcols as those records in weapons and armor haven't been decoded (or what ever the correct word would be) yet. But there are modcol formIDs listed under weapon variations.

Right click -> Other- > Build Reference Info, check Fallout4.esm

It appears I had an old version, they are mostly in plain text in the newest version

They're probably just leveled lists for mods. A fiver on the first unknown record being 'level'.