“How easy/difficult do you think it is for a person described in the OP to be able to self-learn the language”
Slonimer,
There are two separate issues here. One is the simple language, may it be loshon kodesh and Aramaic, and then we have the Talmdic language. Meaning, even if you are pretty proficient in lashon kodesh/Aramaic, the Talmud has its own difficulties, let it be its laws of logic, expressions, idioms, structure etc. Something that many kids can not relate to, even if they are smart, for many different reasons.
I once read a book/sefer from one of Israel’s top professional mechanoch/therapist named אור בשבילי הגמרא where he has developed a strategy of how to properly teach kids Talmud.
According to his personal experiences and many of his trained students; many kids who have been labeled as doomed in a typical Yeshiva once they were taught his strategy, they had no issues..
You can probably google the above name to find out more.