Books like "Grasping Fortune" or "The Affairs of Wizards "which are about joining house or guilds, include lines specifically refering to Vvardenfell. This doesn't work on the Mainland and we have no Mainland versions of them. According to Minerman, TR_Factions edits vanilla books to include Mainland topics. This could be done here too. Otherwise one could make a new T_D version of  them. 

Books in question:

Fighters Guild Charter(bk_charterFG): Fighters Guild
Mages Guild Charter(bk_charterMG): Mages Guild
Honor Among Thieves(bk_honorthieves): Thiefs Guild
Grasping Fortune(bk_graspingfortune): Hlaalu
The Affairs of Wizards(bk_AffairsOfWizards): Telvanni

Books that are fine: 

The True Noble's Code(bk_truenoblescode): Redoran
Does not mention any place to join but might still be worth changing.