I finally found this guy’s post explaining that despite “samplers” being under “engines” in the web UI, “samplers” are completely separate from “engines” in the zynthian UI, so it’s hidden in another menu. We have all the samplers under “Engines” on the web but hide the samplers so that they don’t count as engines in the zynthian UI. What the hell.
If there’s a way to make something obscure, counter-intuitive, misdirected, named inconsistently, confusing, broken or literally sideways, the Zynthian UI will find a way every time.
Anyway … I did eventually find where the samplers were hidden, but now I find that the /zynthian/zynthian-my-data/soundfonts/sf2 path which is the correct place to put user soundfonts according to the documentation is not mapped for LinuxSampler or Sfizz. Only FluidSynth has it mapped and FluidSynth’s menu ignores the bank folders I created for to just show every installed soundfont in one big list. So while I did manage to get it to play soundfonts, the Zynthian UI is doing its thing once again in the most broken, counter-intuitive and/or insane way possible.