The problem of Helvetica not showing up in QXP is due to the font conflict occurring b/w the default Helvetica font provided by Mac and the custom Helvetica fonts installed by you. Due to the font conflict, many styles of font are getting suppressed.
In Mac OS 10.7, System/Library/Fonts folder contains 3 Helvetica fonts by default: Helvetica.dfont, HelveLTMM, Helvetica LT MM
Workaround for the issue:
1. Remove all Helvetica fonts from the font folders
a) /System/Library/Fonts folder
b) /Library/Fonts folder
c) /Users//Library/Fonts folder
You may not be able to remove Helvetica.dfont from /System/Library/Fonts folder (in case you still want to remove Helvetica.dfont, kindly go through the links regarding protected fonts mentioned at end of my mail. )
2. Flush the font caches, restart the machine.
To clear the current user’s font cache, first quit all running applications (otherwise, you may see font oddities after using the command), then open Terminal (in Applications -> Utilities) and run this command:
atsutil databases -removeUser
atsutil server –shutdown
atsutil server –ping
3. Invoke Font Book -> Install the Helvetica fonts (which you shared with me) -> In case font conflict pops up for Helvetica fonts, select Ignore conflicts option.
4. Again flush the font caches, restart the machine. In case font conflict pops up for Helvetica font, select Ignore conflicts option.
5. Launch QXP 9.3
You can have a look at below links regarding font management and font issues on Mac
In case you have any query, kindly revert back.