He makes the odd mistake—nothing too serious.

他偶尔会犯错误，但不怎么严重。

《牛津词典》

He's too serious and dedicated, wrapped up in his career.

他太认真、专注，一心扑在事业上。

《柯林斯英汉双解大词典》

The laceration doesn't look too serious.

裂口看来不太严重。

youdao

He believed the problem was too serious.

VOA: special.2010.06.17

He was distracted, he was going too fast, and it ended up causing one death and some serious trauma and tragedy for the rest of the community."

VOA: special.2010.07.01

"And in many cases these courses went too far, I would say, towards the fluffy treatment of serious material, and students could satisfy their requirement by taking such courses."

VOA: special.2009.10.22

Red Hands manager Mickey Harte is relieved that Cavlan's injury is not too serious.

BBC: SPORT | Northern Ireland | The Championship | Red Hands trio face fitness race

For now, all the Mets can do is wait and hope this one isn't too serious.

WSJ: Wright's Injury Puts Mets In 'World' of Pain

Hopefully nothing too serious is going on, and Colbert and his family are safe and healthy.

FORBES: Updated Below