Answer

There is an Ashkenazi custom not to eat them because we do not have a tradition regarding the removal of the forbidden fats and sinews. However, this custom is puzzling for at least two reasons: 1. This involves only a rabbinic requirement of removal, and if we are in doubt whether it was done properly, that is a rabbinic-level doubt, in which case one may be lenient. 2. There are communities that do have a tradition in this matter, so why should those who lack such a tradition not rely on that tradition and learn from it? Ethiopian Jews have no tradition regarding many things. Does anyone think that because of this they are obligated not to rely on the tradition we possess?
And regarding the laws of custom, in my opinion this is not really a custom but a concern, as I defined it in my columns about kitniyot.
Bottom line, in my opinion there is no prohibition.
You can see a more detailed overview here: yeshiva.org.il
https://www.yeshiva.org.il › midrash
The Development of the Law of the Hindquarter Meat | Rabbi Eliezer Melamed | Beit Midrash – Yeshiva website