The dictionary yielded 103 pairs, but all of them contrasted the schwa not with the /ɪə/ diphthong but with two vowels /ɪ/ and /ə/ forming two syllables. This distinction can cause mishearings, but they are not associated with any particular group of learners.
Meanwhile Peter Berry has suggested the pair gluer (machine for gluing) versus glue-ear (a medical condition), which is closer to true minimal pair, though there might also be a stress difference.
The density figure is irrelevant.
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