Re: Multi berry melomel question
I don't think you need to be concerned. 12.9% alcohol is fine. One needs more than 10% to store wine long term.
I add crushed fruit/berries the day I make up the wine mix and add the yeast a day later.
If you desire more of the fruit taste, it is not too late to sanitize vessels/tools and strain the berries out of the wine. Then crush them and strain and add the juice back to the wine. A mesh bag or fine strainer or coffee filter would work well to get juice to add back to wine. If berries are somewhat sweet, you will likely slightly add to sweetness of the final product.
Zone 3b. If you always do what you always did, you'll always get what you always got!