Hi,
When you create an order the system stores a copy of the tax rates used. It doesn't store anywhere which tax rule has been used.
So the best you can do is try to guess which tax rule has been used based on the tax rate but you could have several tax rules with different notes for the same tax rate and thus you wouldn't know which one to display.
So in order to do what you want, you should store which tax rule has been used for each tax rate in the order tax info. However, that information is not available when you create an order so it would mean modifying the core code of HikaShop to add the tax rule data to the tax rate when loading the tax rates when calculating the taxes on the product prices.
So doing it with just view modifications is not possible unless you are in a very simple case with simple tax rules. But in that case, just edit the file "invoice" of the order view and add a condition on the address fields in order to display manually some text or some other text.
