LU
I have a close relative learning at Brisk, and he was the one who told me that if you were Israeli and you spoke english, They considered you OTD. Since he is american, he is allowed to speak it.
There was also an aritcle posted here about a store in Bnei Brak that had a sign in english and Rav Zilberstein ruled that one should not patron a store with a sign in english, in Bnei Brak