Dear Devs,
What I should be able to to is hit the “Select All Military (or whatever) Buildings”, and produce units from whichever building using whatever hotkey I want while “All” buildings are selected. For example, while “All Military” buildings are selected, I want to be able to queue spears with Q, MAA with A, archers with W, horsemen with E, etc. for every unit, each having it’s own unique hotkey. However I cannot do this because when multiple military buildings are selected only some unit icons are displayed.
The problem with the “Fully Remappable” hotkey layout option is that under the hood the coding still relies on part of the grid system which restricts the number of icons that are displayed and therefore selectable. The coding solution to this is (probably) to allow for an arbitrarily large list of icon spaces on the UI grid, but if that list is greater than the number of available display icons spots on the grid then do not display. That way it’s still clickable, but just not displayed. Solution #2: give units priority to be displayed instead of upgrades on the UI grid while multiple buildings are select.
The frustrating thing is I am soooo close to a hotkey layout which is optimized for ergonomic efficiency. I have spent ~15 hours frigging around with the hotkey system and this is my last gripe about it.
As always thanks for all your hard work. If this issue is not considered a bug please refer this to the appropriate dev team. I posted here because I assume it is monitored by some of the actual programmers doing the coding 
Edit: After more testing I realized that some of the coding for this would be slightly more nuanced than I thought - the alternate UIs would need to be handled somehow as well. With the “select all military buildings”
the alt UI adds a layer of complexity. For example the English White Tower defaults to its “Upgrade UI” grid, having to then press Y to enable the unit production options…I think the White Tower and other similar
landmarks should default to having their UI production shown (and/or be included in that arbitrarily long list) rather than its upgrade options.