I got this one module “Absys - The last new age.mod” (available on modarchive and other places) where the first pattern shows the non-standard Mxy effect being used prominently. However, opening the .mod in other trackers shows that this should really be a Cxy effect. I parsed the .mod with my own code, and can confirm that the correct effect is Cxy, not Mxy.
Is this a parsing bug? Or was this intended and I should tick some visualization options from within Renoise?
I see what you mean and I agree with you at a high level.
However, looking into the .mod file using a hex editor, I can see that the effect encoded in the file is Cxy. However, this is parsed as Mxy by Renoise. I was wondering if this re-interpretation is intended or is a bug.