I'm still not sure what to put in the ref tag.

The buses do not have an official name or number. MHD has num 1, but 405401 is a regional line, so there is no number on the bus or the digital display. The buses have long sliding text with <stop>-<stop>-<stop>... where not every stop is included.
The digital table shows the "Final stop name", "platform number", and depart time.

The 405401 line number is only found on the paper linked which is present on the platforms in printed form.

What would you recommend? But at this point I think the most correct one would be leaving it empty (as both ref and name are only recommended according to the wiki).

You are correct, thanks for the review. Added ref:ARRIVA tag for routes in changeset/186003241.

Díky moc

Zdravím, ďakujem za comment. Budem ešte experimentovať v JOSM ale mi nebolo intuitívne ako presuniem node na danú koordinátu...