One way is that we ask and the players tell us.

Another way is to see the codes in their script logs they come to us for help with interpreting, which in turn can tell us their patch level and sometimes type of install (e.g., Steam vs. Origin/Disk or one of the Mac versions),

Not sure why this is a matter of concern. The current version mods on offer here are not designed to work with any patch level earlier than 1.67 (although 1.66 is perfectly okay too since the differences between them were trivial). Some will work more or less okay anyway, others will damage ongoing games or cause them to refuse to load. Earlier patch levels than 1.66 are really only a thing if one is running an unpatched Disk install or a pirated version of the game, neither of which we are able to support here.

Don't know exactly which locked thread you are referring to, but when players insist we hand over or design mods meant to be run on their unpatched 1.22 or whatever install and fail to listen to reason, this is what happens.

We support all legitimate sources of the game.