I think the translation is better as: Mereka merogoh kantong tas mereka; not Mereka menggali kantong tas mereka. "Menggali" is more about "making a hole", such as "menggali tanah".
The literal translation of "dig" into "menggali" doesn't quite do it. To better reflect the meaning in English, the Indonesian translation should be: "Mereka meraih kantong tas mereka".
is it wrong to say: ... dalam kantong tas ...
Why is tasnya incorrect?
"Tasnya" would translate to "her/his/its bag", i.e. singular ownership. I believe the intent here is using "they" meaning multiple people, so the translation would be "tas mereka".
The 'pockets of their bags' is therefore - 'their bag pockets'. So would have expected it to be 'tas kantong' not 'kantong tas'.
Think of it this way: when you're adding an adjective to a noun, like blue shirt, you would say the noun before the adjective. In this case, they are using bag to describe where the pocket is, so you would say 'kantong tas,' not 'tas kantong.'
Is using the word "digging" figuratively in this situation allowed in Indonesian too?