Luzern is definetely a city, as Lugano.
Not up to discussion, they have the infrastructure, population, importance of cities, and are regarded as such by literally everyone. I don't know on what basis someone could describe them as towns. Just because they are officially described as cities doesn't mean that they are NOT cities.
Sankt Gallen, while certainly less important, is described as such on the Wikipedia page: "Today, it is a large urban agglomeration (with around 167,000 inhabitants in 2019) and REPRESENTS THE CENTER OF EASTERN SWITZERLAND"

Biel, on the other hand, can be safely described as a town, although an important one.

Non occupa l'intero edificio, occupa anche l'area intorno all'edificio.

Sì in effetti la chiesa era meglio prima, adesso reverto direttamente questo changeset e cambio quelle piccole cose che avevo ragione a modificare, come i nomi delle vie e delle scuole.

Ho connesso le due strade tertiary, che è buona regola che non finiscano nel nulla

<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.

<(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

<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.

<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.

<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.

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 hope I made myself clear.

[I followed this when creating variants, and when determining startpoints and endpoints](https://www.bregaglia.ch/images/VIA--BREGAGLIA.jpg)

In the rest I simply tidied up all the different relations, creating a relation for the official routes of Switzerland and a relation for informal routes that encompass also the italian part of these official routes.
I.e. the italian part of Via Bregaglia does not have any ref number, but the swiss part, that goes from Maloja to Soglio, has an official number and is part of the official footpaths of Switzerland.
I created a relation for the swiss official footpath and a relation for the Via Bregaglia as a whole.

Right, just fixed :)

Yeah, you're right.
My bad.