Hi Dan,
Thanks a lot for your patience.
From your description and the screenshots provided, I understand the issue is that after you change the columns' order in list settings, when editing an existing item in the list in SharePoint
app, it doesn't display the correct order of the column as you set in list settings.
(if it is not the situation, feel free to correct me.)
First, regarding your question "is there a way to rearrange the order on the form in the app?",
unfortunately it's not available to achieve this in mobile app, we still need to access list settings via bowser. Sorry for the inconvenience.
I test from my side and use the same steps you describe to change columns order in list settings>content type>Item>Column order.
When I go back to the list in browser, editing an item showing the same column order as I have set.
However I see the same behavior in SharePoint app version 4.12.0 (20190905) on iOS as you described, when editing a list item, the columns are in the original order I created them, not showing
the new order.
Really sorry for the inconvenience.
Then I consulted the related resource for this issue, actually the best way to help you troubleshoot the issue is to create a support ticket from Microsoft 365 Admin Center.
Please involve your Office 365 global admin and ask him to create a support ticket in
Microsoft 365 Admin Center>Support>New service request.
The support team there has the correct escalation channel for this case. This is also the most efficient way in handling this kind of issue.
Your understanding and patience is appreciated.
In the meantime, I also recommend you share your valuable feedback by clicking Me on the bottom in SharePoint app>Setting(gear icon)>Send Feedback>Report a Problem. This would also inform
the related team and let them look into the issue.
Best regards,
Tina