What version of Qt can EQL5 be compiled against?

I'm trying to figure out how to get to a stable setup to build my android app on, and after investigating the problems with ironclad on my (mostly) working system based on the defaults recommended here, I ended up in a broken environment and decided to start from scratch.

I'm now looking into compiling everything from the ground up to see where that gets me. However, when trying to follow the instructions in eql5-build/64bit, I end up with numerous errors in the make step.

So, I'm wondering if there are constraints which Qt will work. I'm now trying to compile against Qt 5.12.5, but that doesn't seem to work. Might this have to do with the EQL5-symbols file? Is that linked to a specific version of Qt?

Are there any pointers you could give on how to do this? Or am I barking up the wrong tree and is this a fools errand?

Thanks for any help...