I've discovered some bugs regarding the SE iOS app but recently learned that there are no active personnel on the development team for the apps. If this is the case, is there any reason to post bug reports for these apps as a sort of backlog if development does start again in the future? Or are there really no plans to do so making bug reports a waste of time?
Yes. Based on what I've seen here, on MSE, they are continuing to maintain the app but are not actively developing it. This is what hairboat said on a related question:
As far as I understand it, updating the app for iOS 11 / the new iPhone is part of ongoing maintenance for the app. They aren’t working on new features, but are carving out time to keep it up to date.
That said, Brian later stated that updating the app for the iPhone X seems to require more work than they're able to manage in "maintenance" mode.
Unfortunately, even for an app like ours which supports a wide variety of screen sizes and configurations, updating to the iPhone X will be a major undertaking. Not only do every screen edge hugging elements (e.g., the draft indicator) need to be revisited but every screen needs to be tested in portrait and landscape. I've estimated bare-bones support for X as a 2 month project, but given current product priorities that's no target start-date for the project.
The good news is there's really no path forward with iOS development that doesn't involve supporting the X, so when development resumes it'll need to be the top priority.
So, they do hope to be able to go back to active development on the app but it may not be for a while.
As such, that seems to imply that bug reports should continue to be posted, even if they're iPhone X specific, so they know what to work on when they do go back to active development.