But even if they sent you for 1 sat/byte (the minimum fee) the transaction would eventually be confirmed. You don't need to worry, just to wait.
That's only true if you trust the person who sent it to you. If it's someone you don't trust, you shouldn't rely on an unconfirmed transaction.
If that transaction contains the RBF flag set, it is possible to replace it with a change in (fees, outputs, and amount) and therefore you may be scammed and lose your money.
I remember that it is possible in the Electrum wallet even though the main GUI does not support it[1].
Even if the transaction does not involve RBF flag, it is possible that unconfirmed transactions to be canceled.
Cointraffic looks reliable imo, which is the case of OP...
But what you said is also true for 14 sat/byte transaction, which can take about a day in current network status. And anyone can replace by fee a transaction like this with a 150 sat/byte.
I currently have a transaction that's unconfirmed for 2 weeks. My wallet keeps broadcasting it, but if the sender stops broadcasting, it will drop from mempool after a few days and will never confirm.
This is very strange. About a week ago a made a 1sat/byte transaction which was confirmed in about 3-4 days. Mempool below 3sat/byte was cleared a few times after this. Maybe something is wrong with your transaction?