AQ salt is used for specific ailments and shouldn't be used for everything.. please be careful when saying (and even using it) to use it on an ill fish. In some cases, AQ salt will make the fish worse.
Unsure about that specific tea (but DQ is knowledgeable about that), but not all caffeine free tea is good to use.. Rubioos and Green tea are what is commonly used. But they tend not to actually provide any healing benefits, rather it may keep them calm due to the coloration it provides.
What you are looking for is Indian Almond Leaves as those do provide a lot of healing benefits and very healthy for the fish. Even naturally dried and fallen oak leaves work better then most of those green teas.
If you do go the green tea route be careful and research how much to use, as it is very easy to use too much and very easy to not introduce the fish correctly and end up causing shock and death. Why IAL and oak leaves are preferred by many as they are safer. I try to keep a dried oak leaf at the minimum in my tanks floating on top to help the water, give them a place to build a bubble nest and hide, etc.