under the radar

Prepositional phrase

idiomatic

(idiomatic) Without attracting notice; in an undetected or secretive manner.

Japanese Meaning

目立たずに、ひそかに行動する様子を表す。 / 誰にも気付かれず、秘密裏に実施される様子を示す。

She managed to keep her volunteer project under the radar while it grew into a community program.

彼女はボランティアのプロジェクトを人目を引かないように進め、それが地域のプログラムに成長した。

Sense（1）

(idiomatic) Without attracting notice; in an undetected or secretive manner.

Institutional change has not happened. But it's done quietly under the radar at lots of places.