I think the answer to this is "yes". Well, maybe not a universal language, but we would have to teach the 'reader' a language prior to communicating a complicated message.
Perhaps we should think about the steps that go into teaching an infant human a complicated idea. Start with baby steps and build up to more and more complicated communications.
Just to be safe we should probably go through the entire process in more than one medium. For example, a visual medium in different electromagnetic wavelengths; sounds of different wavelengths, etc. Then they would have a kind of Rosetta Stone where any understanding of our lessons using one medium may help them gain insight through the other mediums.