GNSS network adjustment

Hello. Is this software useable for adjusting a point with GNSS baselines to known CORS stations?
I have the official WGS84 coordinates and also local CRS for the stations. I have 3 baselines calculated via postprocessing of GNSS observations at a new point versus each of the 3 CORS (with RTKLIB). So I have east,north,up baselines. Distances are up to 80km.

I have tried but is seems the up component, at least, is not correctly used. For example using only one baseline with an up component of 600m the new point is calculated with a z value about 600m above the CORS but the ellipsoidal height difference is really over 1200m.

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