Recently I read about a post on another forum that said he (new to GOG.com) was angry because he can't get his cash back.
His reason to apply for a refund: I don't know English.
HIS THOUGHT: The feel-free-to-refund-in-30-days policy is a scam, and he will not buy any more games on GOG.com.

Specify what kinds of refund plans you can provide is essential to consumers, especially those who were drawn by your feel-free-to-refund-in-30-days policy(A.K.A. New customers)(A.K.A. Me. haha)
FYI: I fully accept the refund to GOG wallet plan

For example,
I'm ANGRY! CAN I GET MY MONEY BACK RIGHT AWAY?
We always aim to provide our users with working games, so first, we'll try to get your purchase working on your system. If we can't get it working, we'll get you your money back. No worries. :) (Your FQA)
FOCUS: If we can't get it working

This is one of the situations that you can get the cash back.

More examples,
Impulsive purchase, if you know what I mean. I would like a refund for all 4 games in this order.
Sorry for the burden of the process. (This is me.)
FOCUS: Impulsive purchase

WHAT IF I DON'T WANT TO BOTHER WITH TRYING TO GET MY GAME WORKING? ALL I WANT IS MY MONEY BACK!
Our top priority is to help you get the game working, and this means that we will require some cooperation from you. We won't ask anything extravagant, or super time-consuming, like a system reinstall, but if you absolutely refuse to try anything, we won't be able to determine whether the problem can be fixed or not, and won't be able to issue a refund.
This is especially relevant if there are some glaring issues with your computer, like DirectX faults, or drivers that are ancient or even missing. (Your FQA)
FOCUS: WHAT IF I DON'T WANT TO BOTHER WITH TRYING

This are some of the situations that you can't get the cash back, and you can only refund to GOG wallet.
Unfortunately, your FQA pages about refund policy fail to clearly state the situations that the customers can get the cash back.
I sincerely hope you can clearly state the situations that the customers can get the cash back for new costumers.

Your concerns are unfounded. From the email advice sent to members: source

It doesnt say you will get your money back. It says you can, so that means these wont exclude you from refund. They should list what excludes you from it.

Perhaps you should direct your enquiry to Gog directly, rather than fret about your linguistic interpretation of a very simple sentence? In my experience Gog are always polite and helpful.