It'd likely be totally harmless to disable Auditor and Info if you're so inclined. Clock and Messaging can go too, if you don't want the functionality or replace it with another app. On the other hand, App Store is how you get some of the most important Graphene OS updates, so I'd keep this, at least in the Owner profile. Still, if you primarily use profiles where you have it disabled, you might not get these updates in a timely manner, and that could pose a security issue.
The built-in Gallery might have some functionality not replaced by any third-party application. You'd have to check and compare the manifests to be sure. So, some (maybe relatively obscure) functionality launched from another app might no longer work at some point much later when you try to use it. You're even more likely to run into such issues if you start disabling com.android.documentsui (the Files app) or com.android.dialer (the Phone): maybe somewhat unintuitively, the latter has always been a part of any Android build, even for simple devices with no calling functionality at all, such as e-readers. There's a thin line between what can be done without consequences and what can't, and it's not always apparent immediately when you do it, only later.
That being said, the worst that can happen should be an error message saying something like "unable to launch intent." You can't really disable from the UI anything that'd completely mess things up: for example you can't disable the preinstalled keyboard since that's needed to boot the system. So, what you're considering should be a relatively safe experiment. The question is, if you get some sort of cryptic and obscure error months later, will you be able to trace it back to one of the apps you disabled?
Considering you can simply hide apps from app drawer with a third-party launcher such as the free, libre and open-source Lawnchair: there was a new (relatively) stable major release just yesterday, I'd try this as a solution first. You may even find it to have other aesthetic advantages as well.