So it looks like TESFaith# is the program for me, trouble is it keeps giving me error messages when I try to move cells. I just need to move the landmasses in Lothavor's Legacy (which was quite good) and the New Tear island in Beyond YsGramor to the north.

Any tips?

There is also the total conversion Sword of The Perithia which plays on a (fictive) island off the Morrowind coast. And I'm not sure about the other big total conversions like Myar Arannath, Arktwend or Sea of Destiny.
I would expect all these mods (highly recommended for Morrowind veterans, by the way) to be incompatible with TR - but then you wouldn't want to combine one of those total conversions with Tamriel Rebuilt anyway, as they play in a different world.
My personal method to deal with this kind of conflict is to create a separate copy of the Morrowind base game for each of the conflicting mods, and then copy the relevant files to the respective folder, sometimes together with other mods which work for the respective total conversion (like the Propylon Indices for Sword of The Perithia).