I think you’re in fact downloading an .xrni fil ewhich is a renoise instrument. What might confuse you (or your browser) is the fact that xrni is just a zip file containing samples + meta data.
What happens if you just save the xrni on your computer and load it (as instrument) in renoise?
Anyway, at this point, I think you better provide us with one of the instruments in question. Just give a link to where you downloaded it. Then we can take a look at this weird problem
When I have the DiskOp in sample mode, the .xrni files do actually appear, but they’re displayed below any .wav files that are in the same directory. Even when I attempt to load the instrument via sample mode, it does in fact load correctly and has the correct key mappings and settings. Quite odd!
Haha, that’s funny, because I made the exact same suggestion in another thread not long ago. I just remembered it a few moments ago, and was on my way here to suggest it.