Thank you for your post! I briefly looked through the forum and noticed that you are not the only person who is having issues with CesiumJS on Safari.
If these problems continue, I can work with you to submit an issue on GitHub. What version of Safari are you using? Are you on an M1 Macbook? I can also take a look at your code to ensure that your code isn’t the source of the issue - can you send a sandcastle demo?
Best,
Sam