Are you sure you are loading them in correct load order and using bash tags correctly,
The Cosemetics Cobl or RBP files need to load before the TT4OOO.esp itself.
Checked with Bash 2.90 checked it this way by selecting it merge and npc faces worked, added nomerge and did not select it under merge patches only under npcfaces and same results. Eye/Hair are assigned correctly and Changes from TT4OOO are carried over correctly has well.
So check your load order and make sure you have lastest Bash Installed
Thanks...
The current BOSS master list loads Race Balancing Project relatively late in the load order, well after TT4OOO. The TT RBP patch is loaded after bgBalancingEVCore.esp.
So, for the average person who uses BOSS to sort their load order, right now the RBP-TT patch is going to load well after the regular core Travelers files including TT4000.
With respect to the Bash tags themselves, the other components that change NPC faces that come bundled with RBP all have the {{BASH:NpcFaces,NoMerge}} tags, e.g. "bgBalancingEVOptionalNPCDiversity, Vanilla.esp" and "bgBalancingEVOptionalNPCDiversityLAME.esp" both have that tag.
While the issue could be addressed by moving the load order (in which case it should be requested in the BOSS thread I would think), I think another way to look at it is this: are there any circumstances under which you would want to import/merge anything from "TamrielTravellers Cosmetics Cobl or RBP.esp" other than NPC faces? Without the NoMerge tag, things like stats can be imported. I believe with the NpcFaces, NoMerge tag, the *only* thing that will be imported into the bashed patch is the faces. The esp file is inactive, just the faces get imported into the Bashed Patch, and the stats and everything else from the core Travelers files are retained and unchanged. At least, that's my observation, and given that's what I'm assuming the intent of the plugin is I would think that would be desired?
Note that I've also seen similar combinations with other mods for things like armor and books where the sole intent is to replace graphics, but the desire is to avoid changing stats. Examples would include Armamentium female.esp, ArtifactsFemaleArmor.esp, EVE_KnightsoftheNine.esp, EVE_StockEquipmentReplacer4FCOM.esp, Fransfemale.esp, GrimbotsSpellTomes.esp. In those cases the tags are {{BASH:Graphics,NoMerge}} because the idea is just to import the graphics without potentially overwriting other stats.