At the moment, the only option to fix the behaviour you are seeing is to increase the range of the QSliders and build from source, unfortunately. In version 5.0, it will be far easier to fix that without building from source. The behaviour you are seeing is somewhat necessary as both must be in sync: moving slider changes value, changing value moves slider.
As for testing, I did not mean anything exhaustive whatsoever. Just making sure the issues you have mentioned have been addressed in 5.0 would be enough. I like very much the details, like the ones you have mentioned, that’s all.