As an update to this, we implemented a convenience method for moderators to instantly wrap a post in spoiler tags. It also sends an automated warning PM, similar to the one found in the OP of this thread, but warning about the user's post being marked as a spoiler.
Related to this, you've probably noticed that the Edit and Report buttons look a bit different and are both moved to a consistent position on the bottom right corner of the post. For us in the staff, the amount of buttons on each post was getting pretty ridiculous, so to be perfectly honest cleaning up the buttons row is a QoL feature mainly for us, lol. It'll be useful for future user-facing features as well, though. For example, when the Quote button gets (eventually!) added, it'll be located neatly next to the existing buttons.
More concrete updates coming hopefully soon, both to the forums and the site in general.