I've rechecked, that's nearly impossible to do. Keyboard tooltips come from an hidden place that we cannot access.
To build a keyboard tooltip, game just do a TooltipControl:method(), control can be ItemTooltip, PopupTooltip, etc
Methods are thoses of the object type "TooltipControl" (CT_TOOLTIP)
And controls are defined in the c++ side of the game.
Just try by doing a :
/script PopupTooltip:ClearLines();PopupTooltip:SetLink("|H1:item:56490:370:50:26841:370:50:0:0:0:0:0:0:0:0:0:28:1:1:0:464:0|h|h");PopupTooltip:SetHidden(false)
It will show you my sword
Inside SetLink() is used the equivalent of the Lua function we use to get info, ~ same as Lua but in C++.
The other way to do it is to change itemlink passed as argument by another one. I should need an itemlink builder and hope that ZOS added something in their intemlink engine builder to change quality of potions.
, but changing the itemlink will broke a lot of things, quantity displayed in bags, bank, addons which look at the itemlink, maybe values of the potions, etc. It's a hard work for maybe nothing relevant and too much modification for a so little tweak that ZOS could do easily.
The last possibility will be to rebuild ItemTooltip & PopupTooltip themselves by another thing, like GamepadUI does.
That's a lot of work for just a tweak, even, if I already rewrited complete tooltips (ability ones) in another addon, rewriting ItemTootip and PopupTooltip will need me to rewrite entirely the equivalent of esoui\ingame\tooltip folder which is for 90% of its code devoted to GamepadUI and needed for this modification