I mean, she's over 4000 years old and while Harkon and company have had time to update their language, Serana has been locked.

Moreover, it's very unlikely that you speak the same "base" language as her (yours has evolved through time) but even if it was, so many years would have made any intelligibility impossible.

In TES, languages evolve, disappear, etc, yet it seems that you can speak with someone who hasn't had contact with the world for 4000 years with no problem.

What do you think?

PD: I don't know if it's exactly 4000 years, but I think you understand what I mean.

The Tardis automatically translates every language the player character hears...