Bulk change (Edit Issues) should not be possible for fields that are not part of the EDIT screen.

A field content (native or custom) can be modified via Bulk change (Edit Issues), even if the field is not part of the EDIT screen. This is not consistent with the behavior of the simple Edit operation. When a a field is not part of the EDIT screen - it cannot be modified when the Edit button is clicked - it cannot be modified via the inline edit, but anything can be done via bulk. If a field is not part of the EDIT screen then it's because it's not supposed to be updated via any EDIT operation.

Just to provide more detail: In certain Jira implementations, some fields are supposed to be modified only during particular transitions. These fields are not supposed to be edited via the edit operation. In order to accomplish this we add these fields in the VIEW screen (so anybody can see the content at any time), but we don't add the fields in the EDIT screen (so these fields cannot be update via the edit operation / inline edit). The fields are added only to screens that are displayed during the transitions when the fields are supposed to be modified.
Everything works great but the problem is that if you perform a Bulk change (Edit Issues), everything can be modified, even the fields that were NOT supposed to be editable.

It would make sense to take into account the EDIT screen for all Edit operations, including Bulk Edit too.