You don't think we read the cutscene (um, wrong, but enjoy your delusions) and I think you read into it things that weren't even there. Nothing in the cutscene supports your idea of revenge, esp with the backstory, except what your imagination adds.
imagination is a wonderful thing, but it does not make your interpretation based on your imaginings fact.
All they do is mention the ship was at Malachor 5 - that's it. No "Now we shall have our revenge against...um... this ship... yeah, that'll show...it." Just, yes, this ship was pulled from the graveyard of our worst battle ever. I found it an interesting touch of remembrance - not an indication of revenge.
If you can point to some actual line or even something from the load screen that says flatly the Mandalorians were seeking revenge, I'll listen.
But nothing like that exists.