I have following idea for station extension buildings - that is based on experience with building of them.
Current alignment (without regard of binding to any kind of transportation) causes that if any extension is built before station of kind of transportation that is written in waytype extension is aligned to station ti which is extension built.
A little simplier: extension for railways should be built aligned out of other ways. For example, if extension for railway stations will be built to road station (because own railway station will be built after building of its extension) in the south of future railway station, then other alignment should be used - to waytype binding alignment could be kept.
The mean, taht there are already tracks and the building is used for railways in the end; both may not be met a all ...
... oh, ...
My idea is based on two things:
1. station buildings had been built mostly before own tracks
2. if you need to have tracks separated from else kinds of transportation (for some reasons), then station building has to be built before platforms - else railway station will have different name from for example bus station - and sometimes it is only one way how to build whole station