How to type in backtick and tilde in Safar in macOS?
Go to 'System Settings > Keyboard > Keyboard' and check option 'Show viewers for keyboard, emoji, and symbols in menu bar' (see picture).
Then click on flag in the menu bar and select 'Show keyboard viewer'. Keyboard with your current layout shall appear. Check that you have there 'back tick' and 'tilda' symbols. Try to print them in the text field pressing buttons of this on-screen keyboard with your mouse.