They don’t need to worry about the source of the hydrogen to do that. If they were genuinely using green hydrogen (from renewable resources) as opposed to blue (from fossil fuels) you’d expect them to trumpet that, but they don’t even mention it. There won’t be any CO2 saving unless the source is renewable ... if not, you might as well keep burning the natural gas without going through the faff of turning it into hydrogen first.
Absolutely, it's a trial of the Hydrogen infrastructure (transmission, domestic and industrial equipment), not of the creation of it. By the way, Hydrogen isn't made from natural gas, that would be daft as you say. It was made from coal, hence it was called coal gas, or town gas, as it could be made locally in towns, prior to the creation of the gas national grid. The hydrogen/natural gas blend was in use prior to the conversion to natural gas and is still in use in Europe.