What language should I learn (other than English) for science/tech content?

Python

A good idea is maybe to focus on the English and the science/tech content, not on another language.

Latin and maybe some Greek, for deciphering terminology, perhaps?

I would assume Chinese as the only language worth learning for this purpose, as in the western world all science or tech will be available in English. Chinese, however, might enable you to access otherwise unavailable knowledge.