While there are people who are definitely nationalistic, it could just be that they prefer their ethnic language because their EC Church is, as is common in the East, the complete expression of their spiritual/cultural identity. There are those who speak English in all other social contexts, but prefer to have the DL in Ukrainian.
I know many young people in the UGCC who are against English Liturgies and would never attend them. Others are different.
Your point, however, is very well taken. Growing up a cradle UGCC, our Church was always “OURS” that is, “Ukrainian.”
It is, in fact, the Church of Kyiv which has always had more than just Ukrainians/Ruthenians as members. I’m proud that this Church is attracting people from other nationalities. It means that it is fulfilling its Christian mission.
My parish of St Nicholas in Toronto is an all-Ukrainian parish and will be so for the foreseeable future.
And it’s also about the calendar. My friends who go there traditionally use the “I’m busy at work” to attend Church in the years when the date of Easter, for example, is different.
My dear friend, for whose children I am the Godparent, let’s call him “Ian” (because that is his name) simply couldn’t get his sorry cludius maximus out of bed to come to Church for the morning Great Friday services. His mother in law asked me to call him from Church (I went outside with my BB). It was 11:00 am and he still wasn’t ready with the family . . .
And I’ll admit that I lost it and called him a few names. (Is that really sinful, according to Aquinas though?

). And when he FINALLY arrived, his mother in law went to confession and then did something quite unbecoming, raising her voice loudly so that all in Church could hear about how bad he was and how the priest should read him the riot act. That was inappropriate, but I wanted to applaud her!
But Ian, like others, is so used to NOT going to Church using the calendar as an excuse that even when it is a year when the holidays are together, he and his family have trouble.
And that is worrisome to the nth degree!
Alex