Anaplan's "SUBSTITUTE" formula has three arguments whereas excel's has a fourth optional argument that would allow for much simpler identification of specific substrings within a string that varies in construct:
Anaplan = SUBSTITUTE(Text to search in, Text to find, Replacement text)
Excel = SUBSTITUTE(Text to search in, Text to find, Replacement text, [Instance to start from])
i.e.
Text line item =
TR_111_909_G
D_1_2_UYH_LO
SUBSTITUTE(text line item, "_", "|", 3)
---> TR_111_909_G ---> TR_111_909|G ---> G
---> D_1_2_UYH_LO ---> D_1_2_UYH|LO ---> LO
etc.