Yes it is spelled correctly
You have spelled 'still' correctly.
Yes, engineer is spelled correctly in your question.
Flattest is spelled correctly. The others are spelled: silliest, biggest and sweetest.
make sure you are sending it to the right person and that everything is spelled correctly
Yes, surprisingly is spelled with an S. Surprisingly is how you spell it. You spelled it correctly.
You've spelled it correctly.
Convenience (easy access or availability) is correctly spelled.
yes, that is correct.
It should be foreign.
No, "infrachrondal" is not spelled correctly. The correct spelling is "infrachondral."
Correctly: How did Elise spell? She spelled correctly.