My main confusion is that a similar project in Coquimbo/La Serena has not been deleted despite also not being confirmed.

To be honest I don't care enough about, nor have enough time to continue, this seemingly pointless discussion. As someone on that forum alluded to, the specific categorisation of this line is not important enough to warrant fierce debate. While it is obviously a light rail line, as evidenced by its complete lack of level crossings and sharp turns, the small number of people who would benefit from the small extra convenience of seeing it labeled as such on OSM is not significant enough to warrant a war. To those who ignore evidence and preexisting examples of this exact type of system being labeled as light rail in OSM (in of Köln, Dortmund, Essen, Duisberg, Northeastern Paris, etc.), you win. Have a nice life and be content in the 'knowledge' that your favorite Poznań does not, in fact, have light rail.

This discussion did not reach an agreement between many people, and the main argument for this line being marked as a tram rather than light rail, seems to have been that other systems called 'Szybki Tramwaj' are far less grade-seperated than this one. For me, a light rail system should be categorised as such not because of its name, but rather because of its characteristics. Furthermore, if this discussion DID reach an agreement, it leads me to wonder why a planned line of the Kraków Fast Tram has been labelled light rail for more than 10 months without protest. This demonstrates inconsistency not only between various light rail systems globally, but also specifically between szybkie tramwaje in Poland. I suggest this line's category should not be changed until a true concensus is reached.

'Light rail (or light rail transit, abbreviated to LRT) is a form of passenger urban rail transit that uses rolling stock derived from tram technology while also having some features from heavy rapid transit.' - Wikipedia
Plenty of cities have light rail lines that are used by trams. For examples marked as such on OSM, see Köln, Dortmund, Essen, Duisberg, Northeastern Paris, or any number of other cities with mixed systems. Also, regarding your claim that 'reverting… is not allowed', please bear this in mind next time you revert a change, so as to avoid hypocrisy.