Oreg2 (2022-08-21 00:58:01+00:00): I'm afraid you have not answered my main question:

1) Why did you decide to delete the existing relations (Via Panoramica and Via Bregaglia) rather than modify them? What was wrong with the relations you deleted?

You do say this:

2) >>Two other things: the map comes from the website bregaglia.ch, that is the official tourism website for the Val Bregaglia, so nothing particularly untrustworthy, and, just to be precise, I deleted only one relation.
>>That one relation was the italian Via Bregaglia segment, as there is no such thing as the italian Via Bregaglia segment, there is only the Via Bregaglia as whole and the officially-sanctioned Maloja-Soglio segment.

I didn't notice you deleted an Italian Via Bregaglia segment. But you definitely deleted at least two more relations, as I pointed out in my original post: 14414965 and 14414854. The latter conformed to the map on Outdooractive maintained by the local tourist office, which I don't trust (see below). I was hoping somebody would confirm that this map is wrong and delete the route for that reason but I'm not yet convinced that you have a reliable source to confirm this.

And I do need to understand why you deleted the previous Via Panoramica.

To your other points:

3) <Your source is only a schematic map that doesn't even include the Bondo variant>
>>How is this relevant, I didn't delete the Bondo variant, even if it was not shown on the map.

It strongly suggests that your map is not reliable. It may be incorrect or outdated. The current official web page for the Via Bregaglia is this:
https://www.bregaglia.ch/de/aktivitaeten/sommer/la-via-bregaglia
It does not include your map. However, even the map they show on this page is not consistent with the per-stage maps they link to on Outdooractive.com. It seems that Bregaglia.com is not very reliable.

4) <They were based on surveys, GPS traces and current information from the responsible tourist office.>
>> I changed only the relations, I didn't change any actual segment of the routes, so this point doesn't make sense.

A survey and GPS traces of the actual signage on the ground are certainly a more reliable source than contradictory maps on the web. Given the contradictions of the material on Bregaglia.com, the physical signposts might be the only reliable source.

5) <There are no signposts along the way after Soglio, are there?>
>>Yes there are signposts that have written "Sentiero panoramico" on them, and moreover I followed the map from my first answer that shows that that path goes from Casaccia to Prosto.

If there are signpost for a "sentiero panoramico" then that's not the same as the "Via Panoramica" — even if it means the same in two different languages. According to the official web page (which I take to be much more reliable than Bregaglia.com), route 796 clearly ends in Soglio:
https://www.schweizmobil.ch/de/wanderland/routen/route-0796.html
How about leaving the Via Panoramica as Switzerland Mobility defines it and have a sentiero panoramico start where the Via Panoramica ends?

6) <(The Via Bregaglia actually doesn't have a number on the Swiss side, either. I guess you meant the Via Panoramica.)>
>>Yes it has a number, it is simply not shown on the guideposts, https://de.wikipedia.org/wiki/Via_Bregaglia

I'm afraid the Wikipedia page confuses the Via Panoramica and the Via Bregaglia. The former is defined by Switzerland Mobility as path number 796 whereas the latter, defined by Bregaglia Engadin Turismo, has no number.

7) <The new Via Bregaglia variants you introduced are actually only dotted lines on your source map, indicating that they are not part of the official Via.>
>>Precisely because of that I didn't added them to the official Via, but I added new relations describing that they were variants; I don't know if they have any official status, but if they are shown on that map it doesn't seem too nonsensical to insert them on OpenStreetMap.

I guess there is multiple ways to think about this. My understanding of the OSM philosophy is that we only want to map things that can be visually identified on the ground. If this variant is not signposted it should not be on the map. But I can accept a different view.