I've tried creating a new company file with special characters included in my Legal Company name and I'm able to create it.
Let's identify if this isn't a cache related issue. Too many files can sometimes be the reason why some feature of QuickBooks Online isn't working. We can do a few troubleshooting steps to fix this.
Please sign out and sign in using a private window to see if you're able to create a new company. You can use these shortcut keys:
For Chrome, press Ctrl + Shift + N.
For Internet Explorer or Firefox, press Ctrl + Shift + P.
For Safari, hold down Command + Shift + N.
If this works, you can access your account with the default browser and clear the cache. It's always a good idea to clear the cache regularly to maintain a clean slate. It is also recommended to use other compatible browsers as an alternative.
Please let me know the results. I want to make sure this is taken care of.