YOU SAID:
Forty thousand fairies fly favourably
INTO JAPANESE
4万匹の妖精が順調に飛ぶ
BACK INTO ENGLISH
40,000 fairies fly smoothly
INTO JAPANESE
40,000の妖精がスムーズに飛ぶ
BACK INTO ENGLISH
40,000 fairies fly smoothly
That didn't even make that much sense in English.