Mozambique-eSwatini needs adding as an update. Completely forgot the China-Afghanistan border so not quite 100% for me alas. Great idea for a quiz though - really testing.
Sorry but I found this quiz a little ridiculous. First instance I tried Albania-Montenegro then Albania-Greece and wouldn’t accept either of them. I think it’s a bit silly it will only accept one specific neighbouring country. Imagine having to guess the one specific country it accepts for China!
(It would be like writing preColumbian or panAmerican.)