This sentence was taken from a BBC article:
"England knocked out by late Romania flurry."
Is this association of words grammatical? Also, are there any more cases in which proper nouns combine with common nouns?
If you mean this
it's a page title, which is similar to a newspaper headline and is not required to be a grammatical sentence.
Country names are often combined with other nouns; in the above it indicates that England and Romania are the national teams of those countries.
England knocked out by America means the England and USA national teams.
English knocked out by Americans could mean Durham Codgers FC lost to Detroit Geriatrics FC.