Polyrhytms with the "pick-up" trick and some questions

[pmc.galoubet]

I have much appreciated the method shown in the following topic:

Sharing a workaround: Found a way to write polyrhythms with the proper time signature displaying.

I found a way to write polyrhythms that have the same bar length and display the proper time signature. I’m sure this will be done natively in the fullness of time, but for now, this a pretty good workaround. Here’s what it looks like in Bach’s “Jesus bleibet meine Freude”: [Bach.jpg] Normally, this is easy to do using triplets and hiding the numbers and brackets (which is faster to do now that there is a filter), but the time signature would remain 3/4. To get the 9/8 follow this procedure: …

by @claude_g_lapalme, and I have occasionally used it, with success as far as printed score, and to a great extent playback, go.
But when I look closer (with signposts shown!) I sometimes see some strangeness. I must say that most of those experiments were done from musicxml import from Finale, and I suspect they are at the origin of the strangeness.
A first example
PastorFido-III-5.dorico (1.2 MB)
If you look at this with hidden TimeSignature signposts, there seem to be way too many of them (which is something that results easily from Finale imports). The section after the double repeat bars has a reasonable number, but there are some 6 unnecessary ones in the first section. I could remove the ones in bars 2 and 3 using the Delete key but not the other ones. On a lark, I tried using the Cut contextual menu item, and it gave the following result!
PastorFido-III-5.fixed.dorico (1.2 MB)
I supect that the bars 4, 5, 7, and 13 had some damage imported from the musicxml, but if this true, then what was it, and why did it stop Delete and not Cut?
A different problem with the next score:
Noël-4-I.fixed.dorico (1.0 MB)
The printed score is quite stisfactory, but the playback has a glitch: the theme (everything before the Variation label) is played back properly with requiredt repeats… but is immediately doubled once. This result fom the fact that my original score was:
PastorFido-III-5.dorico (1.2 MB)
and this one was playback perfect, but difficult to believe as shown, with no visible repeat marker on the top staff before Variation, above the clear double repeat bar in the botom staff! So I fixed it visually with an extra repear bar on the top staff (with the Alt modifier) which produced the redundant repetition above.
I know that the “pick-up” stuff is a temporary trick, so it may have undesired side effect, but this I find this one flabbergasting.
Also, if you view it with hidden Tuplets signposts shown, there is something I do not understand: for the small bar piece of the bottom staff, below Variation, there is Hidden tuplet signpost. But this the only place where there should not be, the Time Signature is 9/8 forced into a 1/4 space, the 3 notes are 9/8 8ths without need of tuplet. If I remove this signpost the 3 notes expand as 3/4 8ths and encroach on the next measure.
Is that another facet of the repeat problem?