I have noticed something which may or may not be a bug, but which I think is undesirable.
In a score where some staves may be cue-sized or smaller, the spacing of double barlines (both double slim and final) match the spacing to be at the 100% staff size. This remains true even if only a smaller (or larger) sized staff remains visible due to staff visibility, and these look disproportionate without a regular-size staff to compare them to. You can see this in the attached screen shot, taking only the cue-size staff into consideration. It appears the same earlier when there is only this line visible.
I don’t know if this has been considered, and it’s certainly nit-picky, but perhaps it can go near the bottom of the engraving tweaks list the team must certainly maintain.
Yes, I’m aware that they must match when there are regular-sized stazes in the same system, but they -also- are the distorted size when only a cue-sized system remains. (Earlier, unpictured, when there is no choir and only the soloist)
That is probably not intentional, but an artifact of the issue you’ve quoted Daniel on.
In that case the only workaround I can think of would be to have another player for the solo places, scaled to 100%, a space size change with system breaks, and playing around with staff visibility… Probably too tricky (especially to manage the part layout!)
If I understand you correctly, you always have only two staff sizes, with the bigger staves at 100 % size, and the smaller staves at a smaller percentage - right?
Try “the other way around”:
Set the smaller staves to 100 %, and the bigger staves to a higher percentage.
In this case, in the bigger staves, the two barlines will look too close (disproportionate), but this “disproportionality” may seem to be a slightly smaller problem.
Besides, the overall music spacing may look better if the smaller staves are at 100 % (meaning normal spacing in the smaller staves, denser spacing in the bigger staves).