Incompatibility with Forgotten Realms, maybe? Either way I had the Researcher join, she spawned as a Planetar. She is able to get pregnant, however when she goes into labor the pregnancy terminates without a new pawn being generated and the researcher does not start lactating.

Hugslib:
https://gist.github.com/HugsLibRecordKeeper/9a6387775bea26d5db31fe28cb2a2eaa

Exact error:
Pawn generation error: Generated pawn incapable of required skill: Intellectual Too many tries (120), returning null. Generation request: kindDef=AC_ResearcherRefugee, context=NonPlayer, faction=Chosen of the Sea, tile=-1, forceGenerateNewPawn=False, allowedDevelopmentalStages=Newborn, allowDead=False, allowDowned=True, canGeneratePawnRelations=True, mustBeCapableOfViolence=False, colonistRelationChanceFactor=1, forceAddFreeWarmLayerIfNeeded=False, allowGay=True, prohibitedTraits=, allowFood=True, allowAddictions=True, inhabitant=False, certainlyBeenInCryptosleep=False, biocodeWeaponChance=0, validatorPreGear=, validatorPostGear=, fixedBiologicalAge=, fixedChronologicalAge=, fixedGender=, fixedLastName=Bospro, fixedBirthName=
UnityEngine.StackTraceUtility:ExtractStackTrace ()
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.Log.Error_Patch2 (string)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.PawnGenerator.GenerateNewPawnInternal_Patch8 (Verse.PawnGenerationRequest&)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.PawnGenerator.GenerateOrRedressPawnInternal_Patch1 (Verse.PawnGenerationRequest)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.PawnGenerator.GeneratePawn_Patch8 (Verse.PawnGenerationRequest)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:RimWorld.PregnancyUtility.ApplyBirthOutcome_NewTemp_Patch2 (RimWorld.RitualOutcomePossibility,single,RimWorld.Precept_Ritual,System.Collections.Generic.List1<Verse.GeneDef>,Verse.Pawn,Verse.Thing,Verse.Pawn,Verse.Pawn,RimWorld.LordJob_Ritual,RimWorld.RitualRoleAssignments,bool) (wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:RimWorld.PregnancyUtility.ApplyBirthOutcome_Patch2 (RimWorld.RitualOutcomePossibility,single,RimWorld.Precept_Ritual,System.Collections.Generic.List1<Verse.GeneDef>,Verse.Pawn,Verse.Thing,Verse.Pawn,Verse.Pawn,RimWorld.LordJob_Ritual,RimWorld.RitualRoleAssignments)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:RimWorld.RitualOutcomeEffectWorker_ChildBirth.Apply_Patch1 (RimWorld.RitualOutcomeEffectWorker_ChildBirth,single,System.Collections.Generic.Dictionary`2<Verse.Pawn, int>,RimWorld.LordJob_Ritual)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:RimWorld.LordJob_Ritual.ApplyOutcome_Patch1 (RimWorld.LordJob_Ritual,single,bool,bool,bool)
Verse.Hediff_LaborPushing:PreRemoved ()
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.Pawn_HealthTracker.RemoveHediff_Patch3 (Verse.Pawn_HealthTracker,Verse.Hediff)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.Pawn_HealthTracker.HealthTick_Patch2 (Verse.Pawn_HealthTracker)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.Pawn.Tick_Patch7 (Verse.Pawn)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.TickList.Tick_Patch2 (Verse.TickList)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.TickManager.DoSingleTick_Patch7 (Verse.TickManager)
Verse.TickManager:TickManagerUpdate ()
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.Game.UpdatePlay_Patch3 (Verse.Game)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.Root_Play.Update_Patch1 (Verse.Root_Play)