Following the feedback, I posted the question in Academia. The answer concerns Quebec

In French North America:

Full professor translates to Professeur titulaire.

A tenured associate professor would be Professeur agrégé.

An untenured assistant professor would be professeur adjoint.

I suppose it’s possible to get promoted to “associate prof” without
getting tenure (the processes of promotion and tenure are generally
distinct), but “tenure” is agrégation.

The notion of “adjunct professor” does not translate to “professor
adjoint” but rather to professeur associé.

I’m not sure there’s an English equivalent to Maître de Conference.
Maybe this is before the “professeur adjoint” level.

“tenure track” translates to “en voie d’agregation” or “avec
possibilité d’agregration”; the latter formulation is used for
recruitment but a professeur adjoint already hired would use the
former.

Actually there is a old similar thread in the same forum. Regarding France, there is an answer that covers French particularities.

In France, the position Assistant Professor is a permanent position.
As research activities are also done in labs in addition to the
universities, the positions are:

assistant professor (maître de conférences) : permanent teaching
position, but can not supervise PhD students alone.

Is typically working towards a habilitation (HDR, habilitation à
diriger des recherches), a longer-lasting standalone research project
of about 5 years, during which the person co-supervised a few PhD
students. After defending the project in front of the jury a person
with an HDR can supervise PhD students alone.

professor (professeur des universités) : permanent teaching position,
can supervise PhD students alone.

full researcher (chargé or directeur de recherche) : permanent
research position without teaching, can supervise PhD students alone
if holder of the HDR.

There is a complete wiki article as well.

EDIT

There is a newer answer concerning France in Academia:

To be honest, the first three title (Lecturer, Assistant/Associate
Professor) were always quite nebulous to me. What you must understand
is that the two systems are completely different.

Basically, if your job is permanent and your activities are split
between teaching and research, you have the rank of a maître de
conférences (MdC) or professeur des universités (PU). Note that the
answer on the “related” question mentions the habilitation à diriger
des recherches (HDR), which is more of a degree than a rank. You need
to have a HDR to apply to full professorship positions, but you are
still a maître de conférences in the meantime. Finally, there are
several tiers within both positions (MdC and PU) based on seniority.

If your job is not permanent but still have to teach and do research,
you are most probably an Attaché Temporaire d’Enseignement et
Recherche (or ATER).

If your job is permanent and only have teaching duties, you are most
probably a professeur agrégé (or PRAG).

And finally, if your job is not permanent and only have teaching
duties, well, you are not really in the academic system and I don’t
think there is a rank or title for that.

So to answer your questions:

No, I believe maître de conférences is the equivalent of a tenured
professor (in terms of service/duties but not necessarily experience).
I have seen some people using maîtresse de conférences, so I guess it
is accepted. All your translations are not valid since they aren’t
associated with anything in the French system. Since there is no
tenure track in France, it doesn’t really make sense to try and
translate it. Extra item: If you are searching for translations
because you are writing your CV, I also recommend what has already
been said in the comments: just use the official title and don’t mind
too much about translating it one way or the other.