Each of the July-August answers contains within it a number in a different languages. (For example, DUET contains “DUE”, which is Italian for the number two.) These languages are represented by the flags. If you replace the flag with the number, the answers all fit in the blanks. The answers are:
(DUE)T – Due is Italian for 2
SU(SHIBA)LL – Shiba is Chinese (Mandarin) for 18
(FIFTEEN)MINUTES – Fifteen is English for 15
ARCA(DEG)AMES – Deg is Welsh for 10
INDI(GO) – Go is Japanese for 5
(TESSERA)CT – Tessera is Greek for 4
(FUNF)ETTI – Funf is German for 5
(SIBSA)NDRENTS – Sibsa is Korean for 14
Given this list of numbers, it makes sense to convert them into letters. Taking A=1, B=2, etc., gives BROJ EDEN. Broj eden means “number one” in multiple Slavic languages, notably in Macedonian. The North Macedonian flag pointing to the Spanish flag at the bottom of the puzzle indicates we need to translate BROJ EDEN from Macedonian to Spanish, giving the answer NUMERO UNO.