@sabrinkmann The error message says that flohmarkt expects resourceConformsTo to resolve to a JSON document, but https://www.wikidata.org/wiki/Q4916 resolves to a HTML page. Technically, flohmarkt is not wrong, because this property is not well-defined in FEP-0837, which only states that resourceConformsTo could by "any URI" (potential improvements were discussed on SocialHub but we haven't reached conclusion yet).
Your Note looks fine, except that hasNumericalValue should be a decimal string, as you mentioned.
Also, the value of to is as:Public, which is not always supported (I don't know whether this is the case with flohmarkt).