One of the constructs of this simple language is: MyVar IsNumber - a true bool if MyVar turns out to be a number.

This is not exactly what you're asking for, but may I point you towards the module Regexp::Common? No need to reinvent that wheel. Then, with

  use Regexp::Common 'RE_ALL';
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at the top of your generated script, the original expression can become:

  $MyVar =~ RE_num_real()
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