The orders are not big but it's constantly coming in.
The orders are not large but it's frequently coming in.
「注文(複数形」」→「Orders」
「コンスタントに」→「Constantly, frequently」
「入る」→「To come in」
まとめて言いますと、
「The orders are not big but it's constantly coming in.」
「The orders are not large but it's frequently coming in.」
と表現します。
どちらでも使えます。