Thanks for sharing your research. I've found something similar, that Canuck Defenders are a Fabarm SDASS derivative, which I believe is close to the FP6.My research indicates that all parts interchange between the HK/ Fabarm FP6 and the Hatsan Escort. The FP6 is a pump tho.
Looking at the H&K SLS 2002 - the internals look exactly the same as a Hatsan Escort Auto. - certainly an HK design.
Looking at a diagram for the Escort bull pup, it’s certainly very close to the original Escort MPA.
I have an MPA that I can compare parts to, when I eventually take it down for cleaning.
Yes this is a Turkish shotgun, but Hatsan isn’t just an unbranded/ then Rebranded hunk of Turkish junk - they are quite well known for reliability and quality.
Edited for greater accuracy