RDF 1.2, RDF-star, N-ary Relations, Reification, Dataset Semantics

I've been out of the semantic web world for a while and I'm looking at 
the published drafts of the RDF 1.2 documents. I'm a bit confused and 
seeking confirmation that my understanding of the problematic, the goals 
of the RDF 1.2 (regarding this topic) is correct and seeking information 
if there are some other initiatives (quite possibly non W3C) on the topic.

A concrete "triple" can be one of the following things:

1. Triple as the meaning intended to be conveyed by it.
2. Triple as a particular assertion (a statement). Suitable for 
asserting that some person believes it (or not), asserted it, when, 
where, how.
3. Triple as an assertion (of a particular triple), a type (or 
existential variable?) of which point 2. assertions are instances.
4. Triple as a particular (subject, property, object) tuple, as an 
abstract, mathematical object. Suitable for asserting that it is part of 
some graph, or relate to an assertion of it (2.).

For a graph analogously:

5. Graph as the meaning intended to be conveyed by it.
6. Graph as a particular collections of assertions (statements). 
Suitable for asserting that some person believes them (or not), asserted 
them, when, where, how.
7. Graph as an assertion (of a particular graph), a type (or existential 
variable?) of which point 6. assertions are instances.
8. Graph as a particular set of triples, as an abstract, mathematical 
object. Suitable for asserting that it is part of some dataset, or 
relate to an assertion of it (6.).

Then there are datasets, as collections of (possibly named) graphs (with 
possibly a default graph).

Point 1. is the most common usage of RDF. Reification [1] allows 
expressions about a triple as in point 2. (being defined based on the 
S/P/O IRI referents, not the IRIs). From what I've read, RDF 1.2 aims to 
introduce a triple as a RDF term to be able to expressions about a 
triple in a sense of point 3.

Both reification and quoted triples don't assert the triple. That can be 
done easily by just asserting the triple (as in point 1.) as part of the 
graph (or use the new Turtle annotation syntax {| ... |}).

Regarding n-ary relations, there are the established approaches [2] 
which work well. There's a way of relating between simple 2-ary 
relations and more detailed relations [3] (a work I've been part of) 
like these:

<#alice> ex:hasRead <#beekeeping> .

<#myreadingevent> a ex:ReadingEvent ;
ex:reader <#alice> ;
ex:book <#beekeeping> ;
ex:when "2010-11-01"^^xsd:date .

 From what I understand, RDF 1.2 doesn't bring anything new regarding 
n-ary relations. However I've seen examples of RDF 1.2 like this:

<#room1> ex:temperature 100 {| ex:scale ex:DegreeCelsius |}.

Surely the domain of the ex:scale relation is a measurement (expressing 
the measurement is in Celsius), not an assertion of triple (expressing 
the triple is in Celsius makes no sense). Are such examples are errors 
and should be corrected and discouraged? If not, it seems to me creating 
a new concept to be used as a domain of relations such as ex:scale which 
would mean the relation expressed by the triple assertion would 
complicate things a lot. As I understand it, this is exactly what 
RDF-star does, introducing the transparency-enabling property [4], but I 
see no word of it in RDF 1.2 spec drafts. Is this still in heavy 
discussions?

Lastly on topic of datasets, which is the most valuable topic for me, my 
understanding that they are out of scope of RDF 1.2 and the status is 
the same as in 2014 note "RDF 1.1: On Semantics of RDF Datasets" [5]. 
Has there been any work (W3C or not) to have a vocabulary allowing to 
express that a particular dataset was created with intent of particular 
semantics as described in the 2014 note?

Personally the existing RDF 1.1 ways of expressing n-ary relations and 
datasets (semantics "Each named graph defines its own context") are the 
most useful tools to me. Perhaps quoted triples are intended to be a 
step towards standardizing dataset semantics?

Cheers,
Jiri Prochazka

[1] https://www.w3.org/TR/2014/REC-rdf11-mt-20140225/#reification

[2] https://www.w3.org/TR/swbp-n-aryRelations/

[3] https://smiy.sourceforge.net/prv/spec/propertyreification.html

[4] 
https://w3c.github.io/rdf-star/cg-spec/2021-12-17.html#selective-ref-transparency

[5] https://www.w3.org/TR/2014/NOTE-rdf11-datasets-20140225/