I see foreigners walking around my neighbourhood, but I don't know where they're from.
I guess it would be strange for me to start talking to them all of a sudden.
この場合、次のような言い方ができますよ。
ーI see foreigners walking around my neighbourhood, but I don't know where they're from.
「近所で外国人が歩いているのを見かけるが、どこ出身かはわからない」
ーI guess it would be strange for me to start talking to them all of a sudden.
「突然彼らに話しかけるのもおかしいしね」
ご参考まで!