I've tried 3 approaches thus far with some success.

1 - In most cases, you can just leave them out and no harm or change to the recipe as they aren't key to the flavour, they are usually garnish.

2 - IF you can find dried cranberries with NO added sugar (very difficult) they can work. Fresh or Frozen Cranberries that have been cooked just til softened and then drained and chopped, can be used for their tartness and colour alone. Won't need very much, perhaps half the amount of raisins called for (and add sweetener if desired at the cooking).

3 - Dried currants or blueberries (if you are sure there is no added sugar) can also do the job. They're not as tart as the cranberries but are closer in texture to the raisins.

I usually just leave them out. The only recipe I've found that they are "key" or important in, is raisin pie. Don't even go there