I frequently need to input chord symbols in a similar syncopated fashion to your example.
I find a combination of the following works well enough for me, from within the chords popover:
- Grid set to semiquavers (or the the smallest subdivision in use), which I can advance with left/right arrow keys
- Hitting space to advance by a beat where that is the next smallest division
- Hitting tab to jump to the next bar.
If, for example the chord change is on a semiquaver push, I don’t have to count 15 semiquavers from the first beat of a bar. I could hit space 3 times then Right 3 times. Or I could hit tab one, then Left once.
That works even if there’s no bassline/notated material yet. If there’s a bassline in place, even better as then you have the added option of selecting any note & bringing up the popover.