Anecdotal, but some French computer scientists I know think language is one factor for their relative invisibility: basically everything is done in French, and much of it is required to be in French. The increasing practice in some other European countries is to allow a greater scope for English in the sciences and engineering.
In particular, any official thesis or report must be in French, which means that the thesis itself won't be widely read/cited internationally, and means that it can't be directly chopped up to make English-language journal articles; the student would have to translate their own thesis to republish parts of it in journals. In addition, they aren't generally required to be able to: since everything official is done in French, it's not necessary for a student to have English writing skills of a level sufficient to write for a scientific journal (though they do generally need English reading skills sufficient to read papers in their area).
In particular, any official thesis or report must be in French, which means that the thesis itself won't be widely read/cited internationally, and means that it can't be directly chopped up to make English-language journal articles; the student would have to translate their own thesis to republish parts of it in journals. In addition, they aren't generally required to be able to: since everything official is done in French, it's not necessary for a student to have English writing skills of a level sufficient to write for a scientific journal (though they do generally need English reading skills sufficient to read papers in their area).