I had a piece in 12/8 that I decided to convert in a 3/4 presto.
I doubled the notes (and pauses) duration (key '+'), changed the tempo signature from 12/8 to 3/4 and run "audit bar lines".
Result: a complete mess.
The whole notes and pauses stayed whole notes, so all the timings were wrong.
I had to correct and rewrite everything by hand.
Work for another user tool?
I doubt I have not checked: doing an "audit bar lines", are the temporary accidentals correctly handled or NWC simply adds/moves the bar lines?
Audit bar lines does not going rip up and re-notate everything in the staff to a new time signature.
If you want this kind of conversion, the closest thing in NWC would be an export to MIDI using the new time signature, then import back to notation.
Also, to keep the bar lines at least where they were originally, wouldn't you keep the note and rest duration the same (rests would likely have to be re-notated later) and change the time signature to 6/4 instead of 3/4?
Changing 12/8 to 6/4 it's easy job.
What I needed was really to have a fast 3/4. (cfr. Chopin Scherzo Op. 31 in Bb)
12/8 converts more naturally to 4/4 than to 3/4
Just going off topic a little...
We have a great bunch of younger people in our worship team at church who play what they know fairly well. BUT, everything is in 4/4 - OK, slight exaggeration, but even most of the 3/4 stuff we have ends up being played in 4/4... Works OK for the most part, but the feel... oh the feel...
And trying to get them to play 6/8 correctly... Still, patience Lawrie, they are coming along and several of them are really very talented.
I made some quick tests and the answer is: yes, temporary accidentals are correctly handled (whew!).