> They are predominantly not catholic, still eastern orthodox.
I don't know what the grandparent meant, but the official name of the Eastern Orthodox Church is "Orthodox Catholic Church", so the phrase "Russian Orthodox Catholics" is technically correct, if prone to confuse the uninitiated. It is possible their native language isn't English, and in their native language, (the equivalent of) "Orthodox Catholic" is a common phrase, as opposed to the confusing obscurity it is in English.
While in popular (English) parlance the Roman Catholic Church has somewhat of a monopoly on the word "Catholic", theologically speaking all Christian groups which accept the Nicene Creed claim to be (or to be part of) the "One, Holy, Catholic, and Apostolic Church" in which that creed proclaims belief, and hence Orthodox and (creedal) Protestants officially believe they are Catholics too. (Some less ecumenically-minded Orthodox and Protestants will even go so far as to believe that they are the only real Catholics, and Roman Catholics are fake Catholics.)
> But I think the eastern orthodox church had some reforms that they did not agree with.
The Russian Orthodox Church decided to abandon some of its own liturgical traditions and replace them with imported Greek ones instead. This upset the Old Believers, and the Church refused to compromise, so they left. Later, it decided to become more tolerant, and allow individual congregations to keep the old practices, so some of them (the Edinoverie) returned. But other groups of Old Believers insisted the reforms were heretical, and hence the Russian Orthodox Church were a bunch of heretics and it was a sin to rejoin them, even if they were now willing to allow the old practices to be retained.