Difficulty encountered by a non-native Arabic learner does not automatically establish that an Arabic word is technically harsh. The learner's fluency and the language's own phonetic norms are separate issues.
Nor does length alone prove tanafur: a long word can be smooth, whereas a shorter word can contain an awkward sound sequence.
Assessment must therefore refer to the expression's phonetic pattern and the informed standard of Arabic usage—not merely a learner's struggle or letter count.