I'm using refined storage with AllTheMods6: 1.7.11 (Minecraft: 1.16.5, Refined Storage: 1.9.15).
I love the mod!
A great way to organize the complexity of different blocks are the filters. See screenshot.

1. There is more room to the top for additional filter tabs, and on the right to show filter slots. Could there be a config option to allow up to 8 filters?
2. Integration with JEI is already pretty good since the crafting grid search also applies to JEI. Could the effect of the current filter be applied to the JEI search as well?
3. The filters are set to either filter explicitly by item, or by mod of the item. If I want a filter for storage stuff, then what I really want is all of the RE items and a few vanilla items (like vanilla chest). So ideally, the mod checkbox should not affect the items in the filter, but the next one being added. So I can mix by mod filtering and by item filtering.

1. https://refinedmods.com/refined-storage/wiki/faq.html#i-have-an-idea-for-a-feature-that-can-be-toggled-on-or-off-with-an-config-option
2. JEI sorting works very differently compared to our filter system. That makes this unfortunately not feasible.
3. The current system allows filtering for multiple mods. I currently cannot think of a clean way to make it clear which slot would filter by mod and which by item.

This would require reworking how the filter works. That will not happen in RS1. Maybe once RS2 has gotten far enough.

Is this request OK if reduced to:
There is more room to the top for additional filter tabs, and on the right to show filter slots. Please increase to as many filters as will fit.