the crank looks a lot like the lower-end stronglight steel crank that i had on an 80s dutch bike i used to have. however, mine was cottered, whereas the OP's is cotterless.

i think i also had the same, or at least very similar, plastic chaincase. most dutch branded bikes used the same stock parts from the same vendors... it was mostly just the frame decals that were different.

instead of swapping out the crankset for one with a smaller chainring, you could just replace the rear cog with a larger one, like a 22T. this is what i did with my dutch bike to make the bike more suitable to the hilly area in which i live. that also meant replacing the chain, but it's still cheaper than doing a crankset swap, and there were no chaincase compatibility problems.