言語は本当に冒険は勉強します

Bom dia,

Would like to say "Learning in Japanese is an adventure"?

Then, 日本語を習うのは冒険です。

If you would like to say " I'm learning through adventure in Japanese", then

私は、日本語での冒険によって学びます。 but can be used in rare situations, I think.

I hope it helps!