Is the Book of Jubilees considered to be on par with Chumash by the Beta-Israel?
The short answer to your question is no: Ethiopian Jews do not consider any text outside of the chumash to be "on par" with the chumash.
The Book of Jubilees in Ge'ez is matschaf kufale (መጽሐፈ ኩፋሌ), the first word of which means "book" (a nominal form of tsachafa, "to write") and the second of which means "partition", or "division" - possibly because the text treats of the divisions of the heavenly realm, amongst other things. There are instances in which Ethiopian Jews have learnt halakhot from this text, and it was considered scripturally authoritative. Today, unfortunately, it is impossible to acquire a Ge'ez Bible: Ethiopian Jews who require a Tanakh in an Ethiopian language (መጽሐፍ ቅዱስ, matschafe qedusa - "holy scritpures") are forced to read one in Amharic. I know of none that contain Jubilees, and while there might be some in Israel that service the Ethiopian demographic, every one that I have ever seen has also contained the New Testament.
My sources, aside from "personal knowledge" (having spent six months studying Ge'ez and about five months with Ethiopian Jews in Emeq Bet She'an) are limited to:
• G.W.E. Nickelsburg, "The Bible Rewritten and Expanded". Pages 89-156 of Jewish Writings of the Second Temple Period (ed. Michael E. Stone; Philadelphia: Fortress Press, 1984), 97-104.
In relation to Ethiopian Jews having derived halakhot from Jubilees, he quotes (on p.104) from:
• Lawrence Schiffman, The Halakha at Qumran (Leiden, 1975), 19.