Beer, that's the huge dilemma here too. Some people like it with raisins, and other people are just wrong
Oh, and actually, I just started looking into the ingredients in the dark syrup sold here, apparently they actually do use molasses in it. But it's not as dark as pure molasses, so maybe a 2:1 mix of molasses and something like maple syrup or light cane syrup would work well. Although, the amount of syrup in that whole dish is so small, that using purely molasses is probably fine too.
By the way, if you want to make a bread that tastes like a Finnish Christmas loaf, make a basic wheat dough, and add about half a cup of molasses and a tablespoon of ground caraway to a dough made with about 2 lbs of flour. Really tasty.
My regular dough is 1 kg (2.2 lbs) wheat flour, 2 tsp salt, 1 tsp dry yeast, 7 dl (just shy of 3 cups) of (lukewarm) water, ½dl (quarter cup) canola oil, plus whatever seasonings I'm in the mood for. Mix everything but the oil together, and work it into a nice dough, add oil towards the end. Let sit in a covered bowl in a draft free, warmish place over night. Then I like to work the dough together again to break all the bubbles and distribute them evenly, and then I put the dough on a sheet of baking paper and lift it back in the covered bowl, and let it rise for a few more hours. Then I take a 7 quart cast iron pot, and heat it in the oven (225C/435F), lift the sheet with the dough into the pot and put the lid on, bake for 30 min, take lid of and slightly lower the temperature, and bake for another 15-20 minutes. After that I lift the bread out of the pot and knock on the bottom, if it makes a hollow sound the bread is ready.
That bread lasts us over a week usually, I just slice it and freeze once it's cooled and thaw in the toaster as needed. Other things I like to season with include caramelized onion, or rosemary, or other herbs, garlic works too, once I made a bread with some leftover tomato sauce for pizza, and basically the imagination is your limit.