What's been updated?

It's an educated guess, but these days it's 64 bit support for MacOS most likely.

That would make sense, they all seem to be dos or scummvm games

You can double check here for whichever games you're interested in.

Yes, versioning is terrible here. Half the games don’t even have a changelog, some have one but isn’t up to date. You can’t get old versions of patches etc. Total mess.

In terms of these updates, I had it a week or so ago, and it was pointed out there was a new dosbox version out, so that could be it. Do note, it does mean you will get the bloated installers packed with galaxy components such as cloud saves and achievements (they ship parts of galaxy with the installers regardless of wether you use it).