Update
I found a different solution that uses nested substitute formulas in adjacent columns to split a word into its individual letters and double letters and then v-lookup to calculate the total scrabble value. I put the double letters in one sheet and the scrabble values of the letters (including special characters like ô, ï etc in another.
The formulas are incredibly long (especially the formula at Z3) and I think there is probably a way to simplify them...but it works.
I also think it could be adapted to other languages easily by changing the double letters and the letters in the scrabble value sheet.
I'm quite pleased with it.
Formulas
Word in A2, Value in B2, Letters in C3-Z3
Letter 1
Letter 2
Letter 3
etc
Value
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