The instruction
SPxPoll2 1,!CPU
will return the board's current dialect in U0 and U1. The actual dialect number is 256*U0 + U1. For dialects <255 U1 is all that you need worry about (which in practical terms means all dialects likely this century!).
Example:
OBLCD_SetCur 1,0 ;Prepare LCD
OBLCD_Text "Dialect: " ;Show a title
SPxPoll2 1,!CPU ;Get dialect
PushU 1 ;Copy to X
OBLCD_UDecDispXVW ;Display