I would suggest having a gameplay programmer who is responsible for event graphs and can also code in c++.
anim graphs, notifies, montages, and state machines are all gameplay programmer jobs. you might be able to hard code those into your engine, but you lose a lot of the flexibility that gameplay programmers need to iterate on new functionality.
if you want to keep artists from messing up code, tell them not to edit any graphs or data without permission from a gameplay programmer. modelers, animators, and writers should probably not even touch the level editor, unless its just to import their assets. level designers, lighting, and sound designers can place actors into a level, and tweak exposed properties, but if they want a new actor, they should ask the gameplay programmer.
FX artists need to use the editor to create their content, but they don’t need to worry about event graphs, and their assets are cosmetic, so they should not affect external states. they probably don’t even need to use the same engine build, they can probably just use a standard build of the editor, without any of your game code.
interface designers also need the editor to make their content, but they should probably be programmers or work in photoshop making mockups. maybe the gameplay programmer should code the menus as well, if they aren’t already too busy doing everything else.
or you can go the opposite direction, and hire technical generalists who can make all kinds of things, and work together to spot each others mistakes. you might be trading reliability for speed, but the iterative designs you get out of that process might be more fun. as long as you have a source control versioning system to make file backups, you should be fine just winging it with a talented group you can trust.