Anglo-Saxons in Iceland. Somehow, the Anglo-Saxons sail to Iceland and settle there, or perhaps are removed to Iceland by the Norse but later end up taking over the island somehow.
Canarians in Madeira. A more maritime Canarian culture (perhaps as a result of more contact with the Romans due to Roman conquest deeper into modern Morocco) settles the island. Perhaps they could even go further and settle Cape Verde and the Azores.
Maldivian Lakshadweep--a stronger Maldives and more disorganised Keralans leads to the Maldivian conquest of the islands and eventual assimilation. Around the time, Maldivians (or their descendent cultures) settle the Chagos Islands, Cocos Islands, Christmas Island, Seychelles, and Mascarene Islands.
Punic Malta (and surrounding islands like Lampedusa) after Antiquity. Basically somehow getting Punic speakers to the islands in Late Antiquity and having the islands remain Punic speaking.
Tocharian Burma. Tocharian speakers are driven out of their cities and merge with the highlanders of the Tibetan plateau (of whom the ancestors of the Burmese were one of those groups). They eventually move into Yunnan, where they play an important role in the Nanzhao Kingdom, and eventually migrate south into Burma and conquer the Pyu city states. The language of the elites, heavily influenced by Sanskrit and Tibeto-Burman languages, is spread widely amongst the people of Burma over the centuries, creating a large Indo-European speaking kingdom in Southeast Asia.
Kalmyk (Southern) Ukraine--bigger and more successful migration of Kalmyks into Russia reaches Southern Ukraine, where they destroy the Crimean Khanate and settle the area in their place.
Currents seem to be favorable for indigenous Taiwanese to sail for Kyushu and Shikoku
They did, that's why there were Austronesian-speaking peoples in Kyushu before they were conquered and assimilated by the early Japanese.