A.L.E.: Since I am still using 1.4.6 - (because I'm working on a project I started a couple of years ago and I don't want to redo all the files in incompatible 1.5.x) - I cannot tell you if there are further issues with Lilypond with the new build.
Nermander: Thanks, and yes, I understand that vector files print better than .png. I have observed that with music graphics even the venerable Oxford U Press - in Taruskin's mammoth history of music of which I have Vol I - prints staff notation examples where the horizontal lines have disappeared because they were too skinny, hard to read and a blot on the OUP's record.
My interest here is in what will work now in Scribus; .png works, .svg has some issues, yes those should be solved, but what to do today? The trick - IMO - to .png graphic files of staff notation is that there should be no skinny lines less than about 5 pixels wide, because they _may_ disappear if they don't match the printer resolution. This is possible with staff notation whereas with many other graphics, and particularly photos or any fine detail, it might not be. I have printed, now, numerous .png graphics in which the staff notation is perfectly clear and legible, even when the same file rasterizes the text enough to be blurry - (lesson - overlay the text afterward in Scribus). Maybe, of course, my standards aren't high enough.
The OP said in his or her most recent post that he or she needed a vector graphic for further work, but no further work can be done on the graphic once it is inserted in Scribus anyway, so it would be reasonable to convert to .png for use in Scribus and save the .svg separately for the further work. This is assuming that the print result turns out acceptably for the purpose at hand, a matter of a test print. A (1) high quality (2) rush job with buggy software is a recipe for frustration, and in this case there is some ongoing issue with the .svg compatibility in Scribus that is not going to be solved today, most likely, and so I am just aiming to help with the "rush job" part and not the "high quality" part, which could be a little longer and which will require the same process of examination of Finale's .svg export, just as with the other issue of Lilypond's .svg, by somebody who understands .svg, to determine what's to be done, and that fix won't be applied to the current stable build, but to the development build.
Another possible workaround may be to re-open and re-save the original vector graphic exported by Finale, using Inkscape or Illustrator, and see if the version saved by Inkscape is then compatible with Scribus.
This is all ancient history now for the OP, but other people may encounter similar issues before all the bugs are worked out of the .svg compatibility.
jack