Is this way to represent crossings good practise?

[Map_HeRo (Mikke)]

Hi and welcome to OSM and our forum again.

@peanuthole

Am I right to assume that Wikipedia-style etiquette would apply here and editing something just to match what I think is right when there isn’t consesus is a bad thing and to be avoided?

As long as you just add details via Street Complete there is not much you can do wrong anyhow. If you start using one of the editors it is always a good idea to have a look into the wiki first, in general here

How We Map - OpenStreetMap Wiki
Good practice - OpenStreetMap Wiki

and for specific issues the respective site. And if you are in doubt about a certain issue it is always a good idea to consult the community here (as you already did … ).