Thanks for reaching out SOY, copying my Reddit reply here incase any other painters want to add their thoughts to it:
The biggest issue I have with the livery editor is how long it takes to create accurate logos.
Painting cars is fun, making the logos is not. A good car can be designed in 2 hours. Creating the logos for said car takes up to an hour per logo, not fun when you have to do 20 of them.
There are 2 ways to potentially make this easier:
Allow .svg images to be imported. Take a look at Gran Turismo Sport for reference.
Allow players to “gift” or share “unlocked” versions of Vinyl Groups. When sharing an item in this way, place a clear warning before confirmation. Something along the lines of “If you share an unlocked version of this item, other players can edit, re-share and upload this as if it were their own. Are you sure you want to continue?”
Gifting allows players to pool together their talents; a strong fantasy painter may not have the precision or graphic design experience of a skilled race painter, but together they can produce impressive work. This was possible in Forza Motorsport 4 however gifting was unregulated back then; I believe that by giving the players a clear warning that gifted content can be re-edited/shared will be enough of a protection for those that do not want their work used by others, while still allowing for “open sourcing” and collaboration.
Everything else in the editor I can live with.
There are some quality of life improvements that I’ve listed below but none of them are critical to my enjoyment of the editor itself.
Ability to categorise saved Vinyl Groups into folders.
Ability to view saved Vinyl Groups in a grid layout. (Gran Turismo Sport)
Ability to paint cars in a plain studio with neutral lighting and/or an outdoor paintkng space (Gran Turismo Sport)
Ability to create and paint windshield banners.
Ability to paint on side/rear windows.
Ability to paint on top of carbon fibre surfaces, Forza aero etc.
Additional typefaces/fonts, such as DIN Pro, Futura Bold and Gotham.
Ability to paint sidewalls of tyres.
Ability to set individual layer groups to gloss/matte/metallic finishes. (Driveclub)
From my old notes here, along with about 100 other (non-Painting) suggestions: https://forums.forzamotorsport.net/turn10_postsm529798_Forza-Motorsport-7-Features-Wish-Lists.aspx#post_529798