The Austrian WKT specification for EPSG:31254 (MGI / Austria GK West), as specified in
is apparently wrong. When using it to convert MGI coordinates to WGS-84, the results are off about 250 meters to the NNW.
It should be replaced by the WKT specification from
http://spatialreference.org/ref/epsg/mgi-austria-gk-west/ - http://spatialreference.org/ref/epsg/mgi-austria-gk-west/
PROJCS["MGI / Austria GK West",GEOGCS["MGI",DATUM["Militar_Geographische_Institute",SPHEROID["Bessel 1841",6377397.155,299.1528128,AUTHORITY
You can verify this by using the https://portal.tirol.gv.at/mapAccelWeb/ClientServlet?CMD=init&VIEWID=-86&MAPWIDTH=807&MAPHEIGHT=569&OVMAPWIDTH=200&OVMAPHEIGHT=122&ACTION=42&LAYERTYPE=2&DRAWSELECTION=true&ZOOM=true&ID=4385&ACTION=0&WHERE=OBJECTID=49638 - official GIS service of the Austrian state of Tirol (German UI only). Use the "x y z" button (tooltip text "Koordinaten abfragen/suchen"), and an online coordinate converter will show up.
I also received a water pipe network map from the town of St. Anton am Arlberg with MGI coordinates, and with the WKT specification from spatialreference.org, the coordinates were transformed correctly, in contrast to the WKT currently included in Geotools.
Maybe other Austrian WKT specifications are wrong too - I don't have a way to check them, but if you have, you might check.