If you wanted to learn a foreign language with the aim of reading classic Buddhist works in their original language, which language would you choose? Japanese, Sanskrit or Pali?

Is it even possible to learn ancient Japanese? I googled a bit and found Nishijima, who said:

(I think that even Japanese, which Master Dogen used in writing Shobogenzo 13th Century, was so much different from the modern Japanese, and so even though I am a native speaker of Japanese,
it was necessary for me to spend 16 years to translate Shobogenzo 98 Chapters from the old Japanese by Master Dogen into the modern Japanese today utilizing 8 hours everyday throughout
365, or 366 days every year.)
So that's a bit discouraging.

Any advice welcome!