Your regex looks reasonable to me, so long as all the words in the dictionary are lowercase. Running it on my local dictionary file gives appropriate results. Could you provide an example of something that was matched and shouldn't have been?

By the way, I find it easier to debug regular expressions when using the 'x' modifier, as follows:

    print if m{
        a.*?
        b.*?
        o.*?
        r.*?
        t
    }x;
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