Oh, dear. Are you aware of the number of colleges and universities that have drastically reduced their programs? This has a lot to do with the dwindling (or null, in some cases,) interest among undergrads. So, a limited number of jobs or scholarly openings- and, to some extent, outside funding for your work. This was DH’s field. There are many subsets and how you proceed depends on your interests. His PhD work and beyond required Latin, German, French and Italian. Other research obviously needs other languages (note juillet’s quotes. After those basics, it could be any language the scholarship is written in.)
But it’s not just language “ability,” the sort most of us get that allows us to read, write and travel. Rather the level of language the scholarship in your interest area is written in (present and past works.) That may take some sleuthing on your part. The language journal articles are written in is important, of course. But those are secondary sources and your own work may be with (will include) original documents. (Eg, that’s where Medieval Latin comes in. Or Medieval German, etc.)
He was able to enhance his Latin, German, and French while actually in grad school. You may need palaeography. Most of this couldbe done during your grad program.
But let me put it this way. D1 wanted an academic career in Medieval. DH went into some panic, knowing how few the opps are. She settled for loving the field, majoring in it and classics, then working outside academia.