pasting Voice 1 overwrites lyrics & staff text

The selection filter affects what is selected, and thus what is copied. It does not affect the factor that postings completely replaces notes (and everything attached to them) with new notes (and those attached things you didn't filter out). Consider again that the passages may be wildly different, different rhythms, perhaps different portions of the song entirely. How would you expect to handle pasting a passage of quarter notes onto a passage of whole notes, or vice versa? Again, under most circumstances one wouldn't want to replace only "some" of the original content when pasting.

So no - it's not a bug, nor is it a flaw - it works exactly the way most people would want it most of the time. For the unusual special cases where you want a different behavior, we provide controls for that, as described. Pasting by defintion loses data - the data in the destination is replaced. That is the entire point of the operation. Nor does it contradict the UI - if you mean, the state of the selection filter, again, that affects the contents of the original selection and thus what you copied into the clipboard, but it does not change the fact that pasting a range selection necessarily replaces what was in the destination.

It is what you are wanting to achieve as far as I can tell. In one place, you have the lyrics you want. In a different place, for some reason that's still not at all clear, you have the notes you want. You can these two things joined, You were trying to do it by copying the notes onto the lyrics. I'm saying, that doesn't work, for very good reasons. But the other way around - copying the lyrics to the notes - does work. And when you're done, you can copy that entire passage to whatever location you want, including putting them in the location where for whatever reason you initially entered rests.

for this particular score, since you already have created this highly unusual situation, your alternate method would "work" in the sense of you'd have both lyrics and notes in the same measures, yes. But it wouldn't attached the lyrics to the notes - they'd still be attached to the rests. So you'd have to then mark the rests invisible, and then still, the alignment wouldn't be correct with other lyrics that were entered more normally into the proper voice.

So the bottom line is, if you don't want to create more work for yourself, don't enter lyrics onto rests if the real goal is to have notes. You enter the lyrics onto the notes in the first place. If you don't know the actual pitches, fine, just enter any pitches you want (eg, using Rhythm mode) then get the pitches right later using Repitch mode.