Indeed. There was actually a meeting of the two Presidents (Xi Jinping and Ma Ying-jeou) a few years ago in Singapore. Iirc they carefully avoided those titles and used something like "leader of the mainland" and "leader of Taiwan" instead to go round the issue. Of course the meeting also happened because Ma Ying-jeou is from the KMT so both sides did at least agree that this was a Chinese domestic issue.