いっても

even if one says; even putting it (a certain way)

→ 言う
phrase Rare #25,792
even if one says; even putting it (a certain way) The meaning depends on the verb and kanji: 言っても means “even if [someone] says,” while 行っても means “even if [someone] goes.” In 控え目にいっても, it means “even putting it mildly.”
JA: 控え目にいっても、彼は愉快なやつではない。
EN: Even putting it mildly, he isn’t a pleasant guy.

いまやめろっていっても無理だ。

Even if you tell me to stop now, I can't.

こんなことをいっても大した慰めにもなりませんが。

I know this probably isn't much consolation, but...

私は彼がいってもよいといった。

I said that it was okay for him to go.

控え目にいっても素晴らしいディナーだった。

To put it mildly, it was a wonderful dinner.

彼の悪口をいっても何もならない。

Badmouthing him won't accomplish anything.

たとえ誰がそういっても、僕はそれを信じない。

No matter who says that, I won't believe it.

控え目にいっても、彼は愉快なやつではない。

To put it mildly, he's not a pleasant person.