The right hand side is not a regex so you shouldn't try to compile it. In the example above you could just do

s/$lhsCompiled{$lhs}/XXX$1/
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If you want to vary the right hand side depending on $lhs then you could do

s/$lhsCompiled{$lhs}/&{$rhsSubs{$lhs}}($1)/
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so that each left hand side can have a corresponding right hand side.