To see if the data is being used then you can check if the Weather Service is publishing the same scale as is being shown in the App. Browse to the the Weather Service endpoint mentioned before (the one with the t/h/p and bt/bh/bp items) and see if that generates the same scale as is shown on the App front page. They may be slightly different as the App only updates every couple of hours.
There shouldn’t be much data stored on the NAS as there is only a few variables so it shouldn’t impact. Just so you know, you could have installed the Weather Service on the OSPi itself if you wanted. Not a big difference just wanted to make sure you knew it was an option.