“cannot join the Jewish people under those conditions where certain mitzvos are ignored or violated since that effectively means she isn’t fully being kabbalos ohel mitzvos, thus rendering the conversion invalid from the get-go.”
I don’t think this is precisely the halacha. Before recent times converts were just taught about a few mitzvos before completing their gerus. This is spelled out quite clearly in the S’A. So lack of knowledge of how to observe mitzvos can’t invalidate a conversion. Instead, what probably matters is the ger’s intention at the moment of intention — did they intend to accept the yoke of all the mitzvos? If so, they’re a valid ger, and if not, not, regardless of their state of knowledge at the time, and regardless of the details of the later behavior (though that behavior of course provides hints about what their intent may have been). In any case, if they join a more frum community later and have doubts about their intent at the time of gerus to accept the yoke of the mitzvos, then they can do a gerus l’chumrah if their rav thinks it’s necessary.