Thanks for the questions!
Massif Press infringement
Hm, you’re right that that section is a bit confusing. I think it’s meant to say “you have to still follow Massif’s third party license” but I don’t know how that bit about products unrelated to LT snuck in that bullet. I’ll raise it with the lawyer to rephrase and focus that point.
As for porting SR or other first party modules — I don’t have much more insight into whether porting them into LT falls under the third party license or not than you do. The “solstice rain” module currently up on mod.io was 1) made before we really had time to work any of this out and 2) already received a request from one of the creators to make it clearer that it was an adaptation, not the real thing. (with which I believe they complied, and haven’t heard anything since then)
If Massif or any of the creators request the takedown of such a port or prevention of further uploads of such, we’ll comply with them just like we would a third-party designer. So if I were a module-maker I probably wouldn’t try doing so without written permission from one of them.
Third-party IP
Honestly, we just didn’t think about the case of you owning your own IP & modding it in. That should 100% be allowed, and I’ll make a note to add something make that clear.