We would like to increase the number of Japanese participants.
We would be happy if we could increase the number of Japanese participating.
Our goal is to increase the number of Japanese participants.
「日本人の参加者が増えたら嬉しい(ありがたい)です。」は英語ではこのようです。
We would be happy if we could increase the number of Japanese participating.
(happy → 嬉しい)
Our goal is to increase the number of Japanese participants.
(our goal is to→ 私たちの目的は〜)
We would be grateful if we could increase the number of Japanese participants.
(grateful → ありがたい)
We would like to increase the number of Japanese participants.
ご参考までに。