Nice proposal!

However, I think the mess will stay for as long as there are two different tagging schemes. Therefore I suggest to abandon either https://wiki.openstreetmap.org/wiki/Tag:highway=bus_stop and https://wiki.openstreetmap.org/wiki/Tag:railway=tram_stop/halt/station or https://wiki.openstreetmap.org/wiki/Tag:public_transport=platform.

My preferred solution would be to:

• Abandon https://wiki.openstreetmap.org/wiki/Tag:public_transport=platform and continue to use https://wiki.openstreetmap.org/wiki/Tag:highway=bus_stop and https://wiki.openstreetmap.org/wiki/Tag:railway=tram_stop/halt/station, because it’s clearer what these tags mean and they are easier to map
• Map https://wiki.openstreetmap.org/wiki/Tag:railway=tram_stop beside the road, where passengers wait for the tram
• Only add https://wiki.openstreetmap.org/wiki/Tag:highway=bus_stop and https://wiki.openstreetmap.org/wiki/Tag:railway=tram_stop/halt/station to route relations
• Map actual platforms with https://wiki.openstreetmap.org/wiki/Tag:highway=platform or https://wiki.openstreetmap.org/wiki/Tag:railway=platform (same as your proposal)