Considering that Renoise is able to use different tuning systems (with this for examplehttp://www.renoise.com/tools/scl-to-xrni), I think there should be some way to map piano roll keys/notes to different notations so that relevant note names for tuning system would appear in pattern editor.
The most convenient way for user would be to be able manually edit and map these note names.
Like this:
5528 