SOUL GUI support?

finally use SOUL to build a Synth and Effect
so my question is
will SOUL support customized GUI design?
or recommend using “Soul generate --juce”
then using JUCE to build GUI

SOUL is going to stay mostly agnostic about how people choose to build GUIs.

Sure, if you’re building a traditional plugin then exporting to C++ and using juce for the GUI will work very well. In future when you’re writing non-compiled patches for loading into DAWs with a JIT engine then it’ll be up to the DAW to provide a GUI system, which I suspect will end up being javascript/browser based.