The issue is not the missing neutral, the issue is that the grid measurment will be wrong. Adding a 230-to-230V isolation transformer does not change that.
In order to correctly use a victron system, single phase or not, in a threephase delta grid, you would need to use a threephase delta-to-star transformer for the whole house, and then use its output as the grid measurment.
Theres been a few threads lately about this. In theory you can correct the wrong measurment through nodered, and use a single MP for example on L1 (connected to L on ACin) and L2 (connected to N on ACin), however the resulting load calculations would be wrong in VRM