Using a foreign language only delays the “enemy”, which might be tactically valuable depending on the situation but the message will eventually get cracked, have no doubt about that. It’s not a secure way of hiding your information and it’s foolish to even consider it. Some forensic dude’s gonna analyze your shit and it’s all going to become 100% transparent in no time at all.

Encryption, on the other hand, can be mathematically proven to be EXTREMELY unlikely to be cracked even by the best efforts of well funded experts, when properly implemented and used.