After running changed rules in this pull request (this bot only tests rules.ini changes):

Changed technologies: SDK.PurrNet

These apps now match: (26) 1595330 2630940 3003650 3098650 3291090 3348510 3392420 3473240 3474110 3669080 3676960 3707400 3724180 3760020 3783760 3791120 3886940 3917010 3946530 3950190 3974040 4026150 4093610 4124720 4210380 4407620

Please confirm that all these changed apps are correct.

Apps seem correct, although there are a lot more known AppID's, but i guess the bot might not own those games?

No it's not an issue with the bot not owning some apps, this is running on all the depots known to steamdb
Do you have an exemple of a known app that isn't in here?
It could be that the other known games are embeding your library's dll in their exe

Also worth noting that we aren't really interested in tracking plug-ins for a single engine

That's completely fair.
Is there a way going forward we'd be able to utilize (& pay if needed) to run a checks on SteamDB for games utilizing our tooling. It's mostly just valuable for internal use!
Cheers.