Changing the order shouldn’t matter, but there is a bug that can result in log warnings if you change names of variables in structs that are used in other blueprints.
The best thing to do is to test.
Close your editor and, if you don’t use source control, make a copy of your project folder.
Open your project and check the output log for any warnings or errors to establish a baseline. Run your demo level where the structs are used.
Make your changes to the structs, save all, and close your project.
Open it up again and check output log for any new warnings or errors and run your demo level again.
If no new warnings/errors and everything looks good in your demo level, you are all set. If not, close out and replace project folder with copied project folder.