Glad it worked! Thank you for your patience and for keeping up with me.
Is it possible to for you to do one more test? Could you remove the title.keys file (keep the prod.keys file) and test it again to see if it works?
I will clean the code with a new version and release the source code. With the new code you won't need to mount the system file; the prod.keys , (he title.keys and the sd path are normally the only things you need to create nsps. I'll clean the need for PRODINFO as well.
I don't know if people also want the possibility to remove the right id and ticket info in nsps (like nxdumptool). If this is something people need, I'll add that as well.