A friend of a friend built this phase converter for me.
T1 - T2 247 V
T1 - T3 223 V
T2 - T3 244 V
That's with my mill spindle running about 1500 rpm in hi range
Not a good balance, the current balance will be about five times the voltage imbalance, which in your case is 10%, so one phase of the motor will be dragging 50% more current then the other phases.
It's likely balanced at some load condition.
If you need better balance , spin another motor as well as the machine tool.
I wouldn't worry about those numbers even if that 223V value is low. T3 is the mfg. leg?