I don't know Fadals, but
G91 H0 Z0
seems illogical to me. H0 cancels the length offset, and G91 Z0 in an incremental move of zero distance, so I find it hard to imagine what I'd be expecting the control to do.
Is there no G28 command available such as:
G00 G28 G91 Z0
or in the machine coordinate system:
G00 G53 H0 Z0
(perhaps G53 = E0)