Hello Zeev,
The easiest way would be to install 14.2 but you might be able to simply open the system.xmp from your star_lib\sip_vc707_ub_fmc667\EDK\vc707
This should offer you to convert the system.xmp towards 14.3. Then delete the content of your output folder, leaving output folder an empty folder. Then retry pressing "Generate" in StellarIP.
Let me know how that goes.
Best Regards,
Arnaud