The Ten Tribes

What is the Rabbi’s attitude towards Eldad the Danish and the laws he renewed?
And even Rashi of Holin cites a law that he is a new one.
And the Geonim also accepted it (although one of the Geonim wrote that due to sorrow and the upheavals of the path, he became confused between the Ḥormat and the laws, which is also found in our day…especially when it is necessary to marry children and there are many Ḥobās).
And also in general, what is the attitude towards groups that are perhaps the ten tribes?