Combine the two hiking route relations [2] and [3] for Via Engiadina into superrelation [1] with the correct segment splits.
I already tried to do that by combining 5 segments into superrelation [1] with CS [4], but only then found out there were two more relations for Via Engiadina. These two seem to be for alternative route segments since in part it runs parallel to [1], and the part in Upper Engiadin (Maloja - Zernez). Relation [3] also contains in part the same ways as already covered in superrelation [1].
I also found some information published that might help in planning the survey:
[5] which only covers the Zernez - Tschlin (Lower Engiadin) sections
[6] Which seems to cover all sections, although with different section cuts.
Since I have not been there, nor live very close I am not planning to visit any time soon. Maybe somebody local can have a look and sort out this messy situation :-).
Cheers,
dikkeknodel
[1] https://www.openstreetmap.org/relation/8478820
[2] https://www.openstreetmap.org/relation/6425401
[3] https://www.openstreetmap.org/relation/2403479
[4] https://www.openstreetmap.org/changeset/61089381
[5] https://scuol.engadin.com/de/angebot/engiadina-wandern-ohne-gepaeck
[6] http://www.wandersite.ch/ViaEngiadina.html

highway and waterway at same layer. Is this a ford, or should it be a bridge or culvert?

All highways on and around Bot Tschavir are mapped as footway. I've noticed on a survey they're actually a mix of paths and tracks.

I updated those that I surveyed today, but there are some left for the next surveyer.

Cheers,
dikkeknodel

Last weekend I noticed that the tracks and platforms of Ilanz are currently being renovated. It seems the lay-out will change, and a pedestrian underpass is being constructed.
Some details are discussed here:
https://www.rhb.ch/de/unternehmen/projekte-dossiers/bahnhof-ilanz
A survey on location is probably required when the construction works finish in 2019.