Japanese are not comfortable sharing their opinions with other people, and they have a hard time standing in unity with others as well.
この場合、次のように言うのはどうでしょうか?
ーJapanese are not comfortable sharing their opinions with other people, and they have a hard time standing in unity with others as well.
「日本人は他人と意見を共有するのが苦で、団結するのも苦手です」
not comfortable ~ing で「〜するのが簡単でない・苦である」
to share one's opinion with other people で「他人と意見を共有する」
to have a hard time ~ing で「〜するのが苦手である」
to stand in unity with others で「他人と団結する」
ご参考まで!