I believe collaboration is the best word you could use here. "Joint effort" or "partnership" would also work, but I would advise you move the adjective "remarkable" if you used joint effort. Ex: "A joint effort between two artists resulted in a remarkable ..." The key question being whether you want to describe their partnership or effort as remarkable, or the results of their effort as remarkable.

I assume, "collaboration" has no perfectly eligible synonym when it's related to artistic realm, at least in this particular context.

we really need to know what the result was then we can best decide on what word to use. collaboration or? but my feeling is collaboration will always be the best word for the way you have structured the sentence. because the result is going to be remarkable.

You could use the word "cooperation" or "association". Some other words that come to mind are "fusion" and "merger". One more interesting word you could use is "synergy". This word is used when two things work together to produce an effect greater than individual efforts. Hope this helps