Selectable available livery list - now you can test this.
https://github.com/Ranran-the-JuicyPork/simutrans-extended/tree/display-which-livery-scheme-this-vehicle-hasDEMO:
Checking multiple liveries can be a little tricky. (´・ω・`)
This is a design issue of the depot dialog as I mentioned above and I believe solving it requires a lot of work. But it will probably see a better solution in the Ves's vehicle manager.
The currently displayed livery is displayed with
"*". If it does not have a livery that matches the selected livery scheme in the list, it shows that another livery is selected by default.
The previous patch listed the livery schemes in the order in which vehicles with a livery were found, but changed them to be ordered by the index of the livery scheme.
Display of other information takes precedence, and if it does not fit on the screen, the display of the list will be terminated.
Only four! 
This would also be complemented by Ves's vehicle manager.
Supplement:
The livery counter counts the number of "livery" in the vehicle.
Therefore, the livery scheme list may be less than the number shown there.
About upgrade information:I made an upgrade icon in the past and posted the demo, but it got lost and it took time to find it. I found it
here.
I'm planning to add a upgrade list display to that patch, as it has additional icons, functions and symbols available, but...
list of vehicles eligible for upgrade is displayed instead of the selectable livery scheme.
In this thread, I posted a demo showing the upgrade vehicle on the convoy detail dialog.

As you can see, the width required to display the vehicle name tends to be wider in phonetic languages such as English - when displaying on the right side, the width may be insufficient. (´・ω・`)
Any feedback on this issue would be greatly appreciated.