Phyletism, or placing one's ethnic identity above the Orthodox Faith, was concemned as a heresy in the 1860's. But even so, it seems as though it's still a problem. For example, is identifying with Russian, Romanian, Greek, etc,... a form of phyletism, or simply jurisdictional? If not, can it? How can we approach the issue?
I don't think anything is wrong with identifying with one's own ethnicity. Phyletism enters into play when you let your ethnicity stand in the way of your religious faith or your communion with other Orthodox Christians (and other humans in general).
If one wants a service in their native language, or wants a festival, or wants to preserve their culture, I don't think that is phyletism.
However, if someone wants their own specific parish completely separated from the others because of ethnicity; then that is a problem. If they don't want to welcome outsiders, or even interact with outsiders due to their ethnicity, then that is phyletism.