While in the past historians like Sir Peter Buck (Te Rangi Hiroa) proposed a northernly migration route for Polynesian peoples that would have seen them travel from Southeast Asia up past Japan over to Alaska and then down to Central America before spreading out into the Pacific; none of the current theories based off the dispersion of Austronesian languages use such a route.

I double checked my own research to see if I could find anyone discussing northern settlements of Austronesian speakers but couldn't find anyone recently making that case. Obviously in modern times the descendants of the Austronesian peoples live in some of those places; but there doesn't seem to be any evidence for a pre-1800's settlement in those areas.

The furthest north settlement looks to have been Necker Island (Mokumanamana) in the Northwest Hawaiian Island Chain. Mythically, Mokumanamana was home to the last of the Menehune, the legendary dwarf people who inhabited the Hawaiian Islands before Polynesian/Austronesian settlement. According to some traditions, the Menehune were largely displaced by the new arrivals who were bigger, stronger, and more skilled in the arts of war; after they fled from Kauai they settled on Mokumanamana as a final refuge. The island does have evidence of stone construction and was a religious site in the more recent past. So there is evidence that it was inhabited on a semi-permanent basis by at least a small population- but its unclear how long this went on. It would stand to reason that the settlement on Mokumanamana was linked to a slightly larger island to the south, Nihoa, which was also probably only inhabited on a semi-permanent basis or if it did have a permanent population it was likely small using hillside terraces to grow food.

Otherwise, the northern tip of the Austronesian homeland of Taiwan is actually not much further South than Necker/Mokumanamana. So if the Austronesians had gone to any of the islands north of Taiwan- those would be the furtherest north reach, but I couldn't turn up anything.