The Wild Shape feature description from the PHB/basic rules says:
You can’t cast spells, and your ability to speak or take any action that requires hands is limited to the capabilities of your beast form. (PHB p. 67)
And the mimicry trait of a raven says:
The raven can mimic simple sounds it has heard, such as a person whispering, a baby crying, or an animal chittering. A creature that hears the sounds can tell they are imitations with a successful DC 10 Wisdom (Insight) check.
As a Druid PC, I've heard all the simple sounds that make up a language that I can speak. So, by RAW, can my wildshaped raven form speak all the languages my character knows? After all I do keep my character's mental abilities when I 'shape', am I able to mimic sounds good enough to speak?
As slowly or weird-sounding as it may be, would it be clear enough for other people to understand?