On your 14.5 sqm you won’t be able to fit all the shrubs you mentioned ;)
Sedges are grasses and should also be planted in groups... a forsythia or hydrangea doesn’t necessarily have to fit there.
But I would see it the same way as my predecessors... write something down... later you will have to decide anyway, because sedge doesn’t match forsythia :D
On a large scale, I would also see it here that after >3 years the planting is "ground-covering".
Unfortunately, palms are only conditionally hardy and thus not suitable as house trees. However, there is a "northern olive tree," namely the willow-leaved weeping pear: looks like an olive tree on the trunk, but is extremely hardy.
Regards