sean,
The CF does not simply recruit people because they want to learn a foreign language. The CF trains people in languages when the CF has a requirement for them to learn those languages, and it is intended to employ them in positions where it would be inappropriate to use interpreters. If someone is already fluent in certain languages, they may be employed at times where that skill is useful, but there are no guarantees that will happen for any one individual. For most other purposes, it's far more efficient to use locally hired interpreters.
If you want to learn a language, then do it. But do not expect the military to offer you that training unless the CF first identifies a requirement for you to have it.