Heidenhain TNC 430 on Mikron UPC 710 5 axis mill datums question

I am trying to understand how to use this old machine that is new to me which seems to function well but I don't understand the DATUMS.
The 0 line in the table puts the spindle near the defunct laser measuring device. Tool change works and has its own datum.
G54 works find but the datum shift codes in either conversational or ISO don't seem to work. The machine originally
had a Blum laser and a Renishaw probe but both are defunct. User parameters are of no help. Perhaps I could get to
the parameters to see what table centers etc are supposed to be? Not sure how to see the parameters.

GF engineer said the datum 0 should be the table center, however it looks more like positioning for laser measuring.
When I try to enter approximate values for table center to line 2 or higher in the Datum table and shift to those coordinates,
it comes up with funky numbers that don't make sense. It does not matter what I put in to the Datum table, there is always
a DRO indication of actual axis positions that do not relate.

I have had great success with 3 axis machining of complex surfaces with Bobcad postprocessor but now trying to do a
4 and 5 axis job with M128 causes X+ limit no matter what I put in for X offset.

Thanks!