Online D&D absolutely can have exactly what you described:
Click → sound starts → tweak a little → done.
You weren’t asking for anything unreasonable. You just picked a tool that made it harder than it should be.
What actually happened
You tried to do this:
“Pre-build scenes, click to start, tweak slightly”
That is a soundboard workflow.
But Syrinscape (Fantasy Player specifically) behaves more like:
“Load a thing, improvise inside it, hope it sticks”
That mismatch is what burned you.
The simple solution (that actually works)
You don’t need to give up sound.
You just need a tool that behaves like a button board, not a weird sandbox.
Easiest working setup (15 minutes, no pain)
Use a basic soundboard app instead:
- Kenku FM (very popular for D&D)
- Voicemod Soundboard
- Soundpad (Steam) ← dead simple
Any feedback? I’ll wait 24 hours to see, before I ask for a refund and never touch Syrinscape again. 
Online D&D absolutely can have exactly what you described: