I don't think it's dreadful, but I do think it is poorly worded. It could easily be reworked into something better and more accurate. For example, it could be reworded into something like this:
We are Catholics, in communion with the pope, who are part of the Byzantine jurisdiction (one of the "Eastern Rites"). Then, there could follow a brief statement to the effect that the "Eastern Rites," which are several, stay true to their Tradition as handed down to them by the Apostles and the Fathers of the Church while being in communion with the Bishop of Rome, the pope. That, in turn, could be a segue into a discussion of the whole concept of different variations of the apostolic tradition within the one overall apostolic Tradition of the Church. Etc., into the rest of the essay.
By the way, the rest of that essay is good. It explains the origins and development of the different rites, and it shows how the Catholic Church includes more than just the Roman Rite. That is useful information to non-Eastern Christians, who would be the main beneficiaries of that essay.
What I find interesting is that it is that one sentence that has drawn ire and comments, while the rest of the website has received little if any comments. I think a word of encouragement and praise is due to the webmaster for taking the time and effort to glorify God online by producing a website that is actually rather good overall and in its several parts.
The website of St. Elias, in Toronto, was mentioned in other posts, and I would like to address that too. The St. Elias site is kind of a benchmark for the ultimate in Eastern Catholic parish websites. But, not every parish website can or should be like the St. Elias website. Every parish is different; and each provides its own, unique testimony to Jesus Christ.
I'm not trying to give some "happy talk" of "I'm ok, you're ok, let's all have a hug." I'm trying to point out that parishes, like individuals, have their own unique merits. Thus, they (and their websites) should be evaluated on their own merits.
As for the St. Stephen website: Yes, it needs some corrections and fine tuning. But, it is a good website as it stands. Hopefully, it will help lead people to Jesus Christ and a deeper life with Him.
-- John