Thanks for sharing your feedback, it’s even harder to come here to give constructive criticism after a bad onboarding experience since you already have lost some time (and money, in your case) and don’t want to lose any more time posting something.
There’s not much Bisq can do for the first transaction. Banks suck, and that’s why we use Bitcoin. You weren’t used to make international SEPA transfers and found an issue that you can’t solve since you are not using a smartphone. The problem is that mediators can’t know if it’s really your first time, and also they need to keep in mind your counterpart which is waiting for your response.
I would like you to share how much was the penalty. I personally think that a small penalty for this cases makes sense, otherwise datamine Bisq users would be too cheap and incomplete trades could become a problem. Defining a “small” penalty is not easy though. For a protocol violation like yours, a 20% of the trading fee could be substracted. Table of penalties - Bisq Wiki
This table was developed recently to make mediator’s decisions easier and more reliable.
At the second one, I take in mind the “panicked” part. It’s normal to feel alone at your first trades and there are many pop-ups. Specially if one of them has the word “error” or similar. That’s why we try to give more personal support through Keybase. Unfortunately people realize about this usually too late. But I don’t know how did you open mediation, the only way to open mediation should be to use the shortcut Ctrl+O, and the button to open it is not displayed until the end of the trading window, which for SEPA is specially large (6 or 7 days). Was it an instant sepa trade?
What bug? What error? Unfortunately, it was simple this time. I just need to close the CLOSE button.
The first you should do, if you haven’t already, is to update to last version. Bisq releases a new version every month, sometimes even earlier for bug fixes. Being updated is very important since compatibility between versions is very low and bugs appear. Releases · bisq-network/bisq · GitHub
This is the first time I see the message on the image and, as you point, it’s not self explanatory. What were you doing before being displayed this message?
Connectivity issues are frequent, specially for slow connections. Application start issues - #2 by MnM
You can contact mediators directly using Keybase if this issue stays for long. Finding your mediator - Bisq Wiki
Remember that after 20 days, trades go to arbitration. Dispute resolution - Bisq Wiki
Point this issue when you get to contact mediation for the second trade.