Sander I think you should default to the entire description and only when someone pushes/taps/swipes allow them to enter an expression used for matching. So anybody who only wants to add a logo can do just that. When they are more experienced they can try to be more helpful. I like Tobias idea as well to have some indication if this is a large chain or simply a local one-off or if you don't know.
I don't know Ali's grandmother so I don't know what she can do, but from personal experience I can tell that sometimes people who couldn't stand new technology and always were complaining about the space the computer took or the amount of time people spent phones can make a U-turn and embrace them when they find out they can use them to see their granddaughter who was born on the other side of the world.
Anyway, I guess you could have some process at bunq to check all the descriptions where no expression has been entered to see if you could create an expression. You might even have a simple matching expression entry ("start with this text", "end with this text" and "this text anywhere") and an advanced with more control. But that'll depend on all the expressions currently used, perhaps and "end with this text" is never used because that's usually were things like city or changing numbers are located.
I don't think you can create a process that won't need any checking at bunq by people workign there. I'm sure bunq wants to weed out the input of inexperienced persons who mess things up. Or trolls adding a KFC logo and enter "McDonal.*" as a RegExp for the matching.
Only if the icons were only used by me (and perhaps the other users joint or connected to an account) then you wouldn't need bunq supervision because no big company would get annoyed 😠 when they find out that the logo of their competitor was used on transactions from their stores.
Or even worse pictures of course; I think trolls are creative enough to find ways to annoy others.