DaiSHobu being translated here as ‘no biggie’ is perfectly all right. The translator has chosen to use a different English/American phrase from what you might consider a ‘direct’ translation of Daishobu which is perfectly fine, and adds to the quality of the translation in that it is more immersive than an otherwise slightly fake feeling direct translation.

I saw her fell down however, is an entirely different matter.

Daijobu = no biggie = fail.