Hello d.langelaan!
Thank you for your feedback, I am Joanna, R&D Manager here at Jimmy Joy.
Answering your question about potassium, we calculate the micronutrient contents and % of daily intake based on the nutrient reference values of EFSA. You can find them stated here, in their EU Regulation 1169/2011 Annex XIII part A.
Apologies for the confusion with the salt content, please consult our following notice about this topic: