Brown properly, in batches. Crowd the pan and the meat steams instead of colouring, and there is nothing later in a slow cooker that will put that back. Let the chorizo give up its red oil first and tip every bit of it into the pot.
Go easy on the stock. A slow cooker loses almost nothing to steam, and four onions and 800 g of tomatoes will give up a great deal of liquid on their own. The 200 ml is a starting point, not a target.
Watch the chicken at the long end. Six to eight hours on LOW is right for the lamb, and bone-in chicken is at the far edge of it. If yours is falling off the bone into the sauce sooner than you want, take the chicken out and let the lamb carry on.
The paprika goes in off the direct heat. It catches easily and burnt paprika turns the whole pot bitter with no way back.