Qool - Thanks for your help!
One thing that is odd: we got this working with the QNAP JRE (from App Store) simply by modifying Ubooquity.sh to look at the JRE installation.
Is there any reason Ubooquity needs QJDK? Another thing of note - the QJDK8 package linked here (currently .71) has a bug - it was not compiled with the x64 binary. Therefore, if you attempt to install the linked QJDK8 and Ubooquity 1.10.1 it will fail to start (ELF32 error on java execute, in other words: "32-bit version only, 64-bit version not found").
I'd argue that if the App Store's JRE works just fine, it may be best to simply remove the "need" for QJDK and simplify - just use the JRE that is installed.
Also, if QJDK is required for some reason, or you don't want to support the native JRE provided by QNAP (via the App Store), note that QJDK8 .71 is very old and has several security holes. 111 has been out for some time now and is a better target.