I "think" you need FORMULA.FIND. I was not able to test.
FORMULA.FIND(text, in_num, at_num, by_num, dir_num, match_case)
FORMULA.FIND?(text, in_num, at_num, by_num, dir_num, match_case)
Text is the text you want to find. Text corresponds to the Find What box in the Find dialog box.
In_num is a number from 1 to 3 specifying where to search.
At_num is the number 1 or 2 and specifies whether to find cells containing only text or also cells containing text within a longer string of characters.
At_num Searches for text as
1 A whole string (the only value in the cell)
2 Either a whole string or part of a longer string
By_num is the number 1 or 2 and specifies whether to search by rows or by columns.
By_num Searches by
Dir_num is the number 1 or 2 and specifies whether to search for the next or previous occurrence of text.
Dir_num Searches for
1 or omitted The next occurrence of text
2 The previous occurrence of text
Match_case is a logical value corresponding to the Match Case check box in the Find dialog box. If match_case is TRUE, Microsoft Excel matches characters exactly, including uppercase and lowercase; if FALSE or omitted, matching is not case-sensitive.