Hi, ofcourse. The reason I made this change is that onderstation is a type of substation that feeds the 25kv traction supply system from the high voltage grid. The ones I changed to AT-station are not connected to the high voltage electrical grid, but only contain an autotransformer that is part of the traction power supply system. Therefore AT-stations don't have a 150kv section. So the function of both types of substation is different.
You can read more about this here: https://www.infrasite.nl/glossary/tractie-energievoorziening-25kv/
I hope that helps

When looking at aerial imagery this transformer does seem to be connected to the 420kV line via the short line on the east side of the substation. Via Google Street view is visible that that short line is connected to the passing 420kV line. From another angle the other end of this line looks connected to this transformer.
I am curious as to what your source is, as the satellite images indicate something else

Ah ja, dat is wel een goeie om in de gaten te houden. Ik heb het op die manier gedaan en aan het gebouw gekoppeld.

Dag,
Bedankt voor de tip, ik heb het bijgewerkt.