Why not use 「波長が合う人」, but 「波長と合う」?
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This is about the difference in the speaker's perspectives. If you asked me, however, if the difference was huge (or very important), I would mostly have to reply negatively.
The former is told from one's （自分） own viewpoint.
"people that one/you get(s) along well with" or
"people that one/you is/are on the same wavelength as"
The latter is told from the other people's （人） viewpoint.
"people that get along well with one/you" or
"people that are on the same wavelength as one/you
The "you" used in the above translations is the impersonal "you".
Hope this makes sense.