Right before paying this weekend, I noticed something which cost me another couple hondo's.
The mains plug was a standard 3phase 32 amps one. The motor should use far less, but I wanted to double check.
At 3 phase 400, indeed the motor uses only 12 amps, but a 10HP motor has quite a surge current when starting up.
I checked with the vendor and indeed, you need a 32 amp circuit to prevent tripping the breakers OR hook the motor to a soft start protection circuit.
So the soft started was added. It's better anyway to have one, and in this configuration they add a 16 amp mains plug, and do startup testing to verify it won't trip a 16 amp breaker.
It's more money, yet again, but on the flip side, these guys assemble and test everything before shipping so if you are not a hydraulics guy, you can know for sure that a) you're working safe, and b) everything works as expected.