Yes, it does help, but perhaps not as much as you would think.
A password/phrase is a sequence of tokens. In a password, the tokens are characters; in a passphrase the tokens are words.
To increase the resistance of a password/phrase to brute force attacks, you can:
- increase the number of tokens in the sequence (i.e. make it longer)
- increase the number of possible tokens used (i.e. use a bigger set of characters or words.)
This is called increasing the entropy of the password/phrase.
An important point it that a passphrase (series of words) is also a password (series of characters). An attacker might attack it as a password or as a passphrase, and it's resistance to the attack is different depending on how the attacker treats it.
If the attacker treats it as a password, the main factor is length (since there are few tokens used in words). If they treat it as a passphrase, the main factor is number of tokens (since the length is so short).
So, should you use foreign words? Well, if the attacker treats it as a password, it makes no difference. Length is length. "chicken" and "oiseau" increase the length be the same amount, as does "skdjnqs" and "aaaaaaa" for that matter. If the attacker treats it as a passphrase, then it does make a difference. Using words from French and English almost doubles the number of possible tokens. So it does help, but as I mentioned, not as much as you'd think.
This is because increasing length is a much more powerful technique than increasing number of tokens. A three-word passphrase in english has an entropy of about 40; a three-word passphrase in french and english has an entropy of about 44, but a six-word passphrase in english has an entropy of 81.
In fact, if you run the numbers, it turns out that adding a single extra english word increases the entropy of a passphrase to 54 - ten more than you get by using two languages. Ten bits of extra entropy means a brute force attack will more than a thousand times longer to run.
So adding another word is a much better way to strengthen your passphrase.
(Although an even better way is to add a small random password with numbers and punctuation!)
Lastly I will mention that the phrases in your examples are not random, which is a weakness against generated dictionary attacks, so you should think about that as well. You want something more like CorrectĈevaloBatteryStaple.