A function that crashes: Compile Error: Procedure too large

[SamT]

First: I notice that you declare ChxLangue As Byte. Since the only reason to use Bytes is to conserve memory usage and since only one value of ChxLangue is used at a time. I would declare it as an Integer. (Bytes are limited to only 254 positive integers)

As to that Too Long Procedure, I would break Select CaseChxLangue into several smaller Functions

Select Case ChxLangue
   Case 1 to 50: LangueRef = ChxLangue1_50(ChxLangue)
   Case 51 to 100: LangueRef = ChxLangue51_100(ChxLangue)
   Case Etc
   Case Esle: LangueRef = "Unknown"
End Select

Function ChxLangue1_50(ChxLangue as Long) As Variant
Select Case ChxLangue
   Case 1: Langue = XLangue
   Etc:
   Case 50: Langue = YLangue
End Select
End Function

Function XLangue() As Variant
   XLangue = Array(ChrW(1040) & ChrW(1084) & ChrW(1213) & ChrW(1100) & ChrW(1231) & ChrW(1096), _
                               ChrW(1040) & ChrW(1096) & ChrW(1241) & ChrW(1072) & ChrW(1093) & ChrW(1100), _
                               ChrW(1040) & ChrW(1193) & ChrW(1072) & ChrW(1096), _
                               ChrW(1040) & ChrW(1093) & ChrW(1072) & ChrW(1096), _
                               ChrW(1040) & ChrW(1191) & ChrW(1096) & ChrW(1100) & ChrW(1072) & ChrW(1096), _
                               ChrW(1040) & ChrW(1093) & ChrW(1241) & ChrW(1072) & ChrW(1096), _
                               ChrW(1040) & ChrW(1089) & ChrW(1072) & ChrW(1073) & ChrW(1096), "Abkhaze")

End Function

Function YLangue() As Variant
   YLangue  = Array("Sennedei", "Monnendei", "Tirsdei", "Winsdei", "Türsdei", "Frideisennin", "Sennin", "Frisien (Nord)")
End Function

Since the various XLangue and YLangue Functions don't Have to be in the same module as NomJourSemaineTrip, think about separating them into Modules named after Language Families or even Continents Anything that makes adding, editing and maintaining them easier. I would keep the "ChxLangue1_50," "ChxLangue51_100" Etc Functions in the same module as NomJourSemaineTrip

BTW, I would use real descriptive names for those Functions, like "FrenchWeekDays," "LangueEnglish," "TagalogLangue," etc. Instead of using "Magic Numbers" to reference languages, I would at least use an Enum.