Like @Kees Baggerman said, depend where the apps are located. I have seen apps that complete dies with 10-20ms latency, which you will have EU<>New York.
Its better to have high latency to the Citrix session then high latency to the apps.
We have user connecting from Japan to Sweden, everything works fine, and we have users in US that connect to Sweden too.
Before I moved Citrix servers to Azure, but did not move app servers as the same time, it was unusable, they couldnt use that app until it was moved.