CLDR 38 introduced the c (with a synonym e) operand for compact decimal formatting. These operands are now actively used in the base plural rules for fr and pt.
CLDRPluralRuleParser only recognizes the legacy operands (n, i, v, w, f, t). When evaluating the new rules, the parser throws an unrecognised word error.
Encountered this while working on T384157: Update plural rules to CLDR version 48