They are primarily concerned with substances that are health risks, which is understandable. There is no mention of hard minerals, namely calcium and magnesium, which might give us a clue (these are the principal minerals contributing to hardness). GH is included in the TDS (total dissolved solids) but so is a lot of other stuff, so this cannot be taken as a guide. If you have no luck contacting them, you might be able to find out from other hobbyists (local club perthaps) or a reliable fish store. Some stores will test water, but make sure they give you a number, not some vague term. Terms like "soft" or "moderately hard" aqre subjective and can be very different depending upon the view of the individual; but actual numbers are absolute, at least within the testing method used.