Side note: Adapting to a libraries style _can_ also been as an advantage
("Obviously code from elsewhere").
In fact, almost all of those questions _can_ be seen this or that way.
Based on some decades experience I can't remember having felt that some
libraries naming convention was problematic for me.
If we want freedom - and I guess close to 100% want freedom - then diverse
styles are a price we shouldn't be too concerned about.
What is beyond personal taste and styles, however, is that whatever (in terms
of style) we write, a compiler should never ever change it behind our back. The
compiler may complain, say about a leading underscore, if a language doesn't
allow it but it must change anything.
Btw. I know the underscore already as (typ.) "digit triples separator" from Ada
and love it. But those are (numerical) literals and not identifiers and
"changing" those '_' (ignoring them) in literals is OK and a different matter.
Btw.2 My own experience with non/not yet Nim users is that they find style
insensitivity exotic, weird, and sometimes funny. I've yet to see a colleague
to _like_ it and to consider it as advantageous (for the sake of fairness: my
group probably does not represent the general developer community)