What is the colloquial Cantonese translation for "还真是"?
'还真是' here is similar to  &quot;It is actually true&quot; in English (agree/affirm to A's statement)
In Cantonese, we would say &quot;噉又係喎&quot;
噉(this) | 又(also) | 係(true) | 喎(final particle: indicate 'agree/affirm')
Mandarin:

A: 他自从遇到车祸以后就不开车了。
B: 还真是，我以为他不喜欢开车呢。

Cantonese:

A: 佢自从遇到车祸之后就冇再楂車嘞。
B: 噉又係喎，我仲以为佢唔鐘意楂車㖭。