Hi supsup,

Yes, I know, the tagging of via ferratas is a long-discussed but never conclusively clarified topic.
At least the mentioned proposal has been accepted in many cases.
I'm looking at and tagging via ferratas in eastern Germany, France and also the Czech Republic for many years and I am in discussion with other via ferrata mappers (e.g. Arminus, sannorra).

We use the following approach for routes and relations:
- Dividing route sections into a relation as soon as different difficulties, elements or variants occur
- Naming of variants in all sections of this variant 
- always "highway=via_ferrata", if only accessible with equipment
- always "via_ferrata_scale" at each individual element (variants, emergency exits, bridges, ...) and for the relation (we have mostly considered the more difficult variant, but not bypassable short extreme variants); this tag is evaluated in XCTrails and displayed in color
- "route=via_ferrata" + "climbing=route" + "type=route" for relations
- "name=..." for relations and, if known, for the individual sections and variants (also displayed individually in XCTrails)
- optional "fee=...", "access=..." and "access:conditional=..." for fee obligation, blocking or access only as a customer, seasonal blocking (the latter is displayed in XCTrails with a cross through it depending on the time).

No standards or best practices are officially available for the starting points. Starting points are also only displayed on maps that actually evaluate this tag.
The approach is as follows:
- Only one starting point for the entire relation (i.e. the point at which you decide on one of the variants). This is the point that can then be displayed on overview maps, e.g. as "Via Ferrata Vodní Brána" with a symbol (in such a view, several start symbols very close to each other make no sense)
- After many tests, I now use the following tags for the starting point, which are not criticized by the quality assurance (Osmose, OSMI, ...) only in this combination:
description=Via Ferrata... (name) 
via_ferrata=start
natural=cliff
sport=via_ferrata
- in XCTrails the tag "via_ferrata=start" is used as a marker where the symbol goes (otherwise the route direction or altitude).

In this case I would suggest
- a single relation with named sections and different difficulties (via_ferrata_scale)
- Names and also colors (but as far as I know no one displays these on a map) for each section.

Hope this helps!
Matthias