I see this has been recently added (March 10, 2019), after the dispute was opened.
At the time of the trade (March 7, 2019), the agreed upon rules were as follows, essentially just exact fiat amount and exact reference text:
If the Bitcoin buyer transfers an incorrect Fiat amount or does not use the exact reference text (offer ID) it is considered a breach of contract. If a trader uses the words “Trade”, “Bisq”, “Bitcoin” or “BTC” in the reference text it will also be considered as contract breach, as some banks are very hostile against Bitcoin blockchain-related transactions and the other peer might get serious problems with his bank. The software UI will alert the user to take care for all those issues at the moment when the Fiat payment is required.
Any additional fees occurring on the sending side must be covered by the Fiat sender. If the receiving bank takes extra fee (should not be the case in our supported payment methods) it has to be accepted by the Bitcoin seller. If currency exchange fees are charged by either the sending or receiving bank, the fees has to be covered by the account holder where the fee is charged.
We don’t support mixed currency exchange (buy bitcoin with paying in EUR but receiving in USD). Some payment methods offers internal exchange and Sepa supports a series of non-Euro currencies. But those cases are handled as the trade currency which is defined in the trade, and the conversion costs are paid by the one with the non matching trade currency.
For altcoin there is no requirement that the altcoin address used in the account setup is used for sending the altcoin. For the receiving peer the altcoin address need to be correct of course.
For those wondering where the rules can be found: