Duwekou40 There should be a line numbers on the side, otherwise it is very confusing
As for the front, the line number displays are not actually digital displays but use a paper strip. VBZ considered it too much effort to print new papers for all the trams.
Duwekou40 Should I report it to SBB to help future passengers?
As Ex-Bähnler pointed out, the trams in Zürich are not operated by SBB, but by VBZ (Verkehrsbetriebe Zürich = Zurich transport operator). You can indeed message them, but to be honest I doubt that anything will change, given that lines 50 and 51 will only exist until december 2026.