Yes, I linked a test page on the opening post already (https://wiesmann.codiferes.net/share/bitmaps/). It has a small test picture on each "popular" format so can easily see which types the browser is able to view and which it has to download to view in external programs. Jpeg2000 is included there.
And this is what the FAQ states:
Quote
"if you are extracting manually then you can register components by going to the K-Meleon\ components folder, locate 2 files named compreg.dat and xpti.dat and delete them. restart K-Meleon and those 2 files with be recreated and they will register the newly added components. please note that registering component files is not required for K-Meleon versions 74 and above"
So it says components should just "work" in modern K-Meleons after putting them in the folder, but it doesn't seem to be the case (or again those dlls are faulty).