Thanks a lot for your comment !
I can confirm that it took a lot of time to learn each part onward and backward and get decent takes (notably with the solo bridging the two parts in one direction and in the other) but glad that the effort was noticed !
Fortunately since I wrote the guitar and bass parts in MIDI initially, I could easily reverse them and see if they worked backwards instead of spending time recording them and having a weak backwards result (still a long process, but more efficient).
Also yeah, recording fretless is always very nice, the Sire bass having very similar scale length and dimensions of my preferred Jazz Bass helps with hitting the right notes without thinking much about it because of muscle memory, so it's pretty smooth on that end.
Anyway, glad that you liked it !