I dug some more on TK17 and the program is at least 12 years old at this point. Maybe even older, TK17 seems to be a modification of a different engine.

http://modsgarden.cc is the TK17 homepage. It's a forum, unfortunately registration is required just to view it. It's active, all subforums have posts made in the last 6 months and there's a lot of activity in the last 30 days. Has a bunch of shared content, models/poses/textures/animations. Maybe some could be imported into Blender? I think the models can only be read by the TK17 program though (they are settings and not meshes).
Their rules don't allow any "underage looking models" and the whole community seems pretty against non-vanilla stuff. Here's a "TK17 Comprehensive Guide": https://gist.github.com/tepiai/b6e99db602b2d8ca38bd0a16c161c0c3

I've concluded that it's probably not worth it to get into TK17 unless you want to make "normal" porn (aka boring porn). The 3D quality isn't SUPER bad but it is looking dated and I think there's additional modding required to make the TK17 3D look its best.