I can't seem to recreate the crash scenario on my device, but if it crashes your app, which it definitely shouldn't do, you can file this as a bug report to SL via the in-app feedback feature. The devs will look into it asap.
at least you have the option... on my iOS app I can only append to the end of tags. I can not insert tags in the middle of other tags. My app crashes often when trying to post edits and when I click on a new notification pointing to someone responding to one of my previous posts. It could be a network issue, but the crashes are frustrating to say the least? 😣