間違いは訂正願います。
①Generally ,We have weddings in churches and then have wedding reception in Japan.
②It is a common thing that we have weddings in churches and then have wedding reception in Japan.
In Japan, it is usual for people to have their wedding at a church with a reception afterwards.
ご質問ありがとうございます。
①Generally ,We have weddings in churches and then have wedding reception in Japan.
➝ Generally, we have wedding in churches and then wedding receptions in Japan.
②It is a common thing that we have weddings in churches and then have wedding reception in Japan.
➝ It is a common thing for us to have weddings in churches and then wedding receptions in Japan.
どちらもほぼ問題ありませんが、①の"we"を小文字にすること、"have"を2回繰り返す必要は無い、そして"wedding"が複数形なら"reception"も複数形にした方が良いです。
ご参考に。
Generally speaking, we have weddings in churches and then have a wedding reception afterwards in Japan.
It's common to have a church wedding followed by a reception in Japan.
takashiさんの英文は次のように言うと良いですよ。
ーGenerally speaking, we have weddings in churches and then have a wedding reception afterwards in Japan.
「一般的に言えば、日本では教会で式を挙げ、その後披露宴をする」
generally speaking で「一般的に言えば」
afterwards で「その後で」
ーIt's common to have a church wedding followed by a reception in Japan.
「日本では教会式の後に披露宴をするのが一般的です」
common で「普通の・よくある」
followed by で「〜に続いて・〜の後に」
ご参考まで！
アメリカ合衆国 
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