FND_MENU_ENTRIES_TL Table storing the record FND_MENU_ENTRIES_TL_N1(MENU_ID,PROMPT,LANGUAGE) wise in R12. But whereas in 11i, records stored FND_MENU_ENTRIES_TL_U1(MENU_ID,ENTRY_SEQUENCE,LANGUAGE).Recreate the indexes and see if it helps.
I am confused, whether i need to recreate the index in R12, so the records will get store MENU_ID,ENTRY_SEQUENCE,LANGUAGE wise.
But OP is asking if he/she should recreate the index. I think he/she should refrain from doing that.Rebuild indexes should be OK.
At most he/she should create a NEW index if necessary.Creating new indexes is not recommended (unless he/she is instructed to do so by Oracle support).