Arrangement with Repeats and DS, DC & Coda

"Here's the catch... the A section has a repeat."

And there's a catch in any answer: nested repeats are not allowed. See a discussion about Nested Repeats from 2019:
https://musescore.org/en/node/284698

The B section has a repeat too.
However: repeats on a jump are not a problem, just tick the corresponding box in the Jump instruction's inspector

So you want A, A, B, B, C, D, A, A, C, A, A, D?

A, A, B, B, C, D, A, A, C, D would be easy, with a Segno at the start of A, a To coda at the end of A, a Coda at the start of C and a D.S al coda (con rep.) at the end (of D)

Problematic is that 2nd jump. Notated in the attached, but not working

Also problematic: A, B, C and D start mid measure, jumps don't allow for that.
You'd need to split the measures (and possibly hide the barlines)

The timing of your melody seems to be off by 1/8th.

Attached a simplified version by moving the score by that amount; fixing the intro timing to match the further score rhythms (if you further equalize the intro timing, you can also use a repeat and volta pattern as in the other parts of the score and reduce another system away; giving a bit more breathing room to your score.

Then as per Jojo-suggestions I've used split-measure at the rehearsal marks for easier score layout. Also noted that since you've had the score shifted, it'd make more sense now to move the repeat barlines up a measure and adjust the volta's accordingly.

I've used the trick of creating a very short (1/64th) additional measure at the end of C to allow for the 2nd jump to perform A-D correctly. We'd almost gotten away without the additional measure because the start of A and D are similar (so move the 2nd jump to the up-beat of D and jump straight into the repeat of A; but this breaks as the jump is then taken again due to it being part of the coda itself as well..

Changed the text of the D.S. and the toCoda to make the roadmap clear for your readers; marked all the other jump instructions stuff invisible.

To neatly hide away the additional short trick measure, adjusted the minimal measure width to 2sp (as low as it can go) and adjusted displacing the rest/barline for it in a similar fashion (also note the minimal distance and leading space corrections on it to minimize it's layout impact). The stretch for that measure is set to 0, while the other measure on that system have been increased one notch (to 1,10).

I've also added a bit of spacers around C, as it is a very vertically crowded part of the score; possibly pulling the 2nd system a bit closer to the first (intro) would make the visual balance slightly better as well.

Used the TempoChanges plugin to apply the ritenuto at the end. Used a system text line for the visual effect.