Add spaces: Twononcommercialjetsandahighaltitudeplanethatcameoutofnowhere.

Answer: Two non commercial jets and a high altitude plane that came out of nowhere.

Add spaces: Thestoriesaboutlargegroupsofgiftedmusicians,architects,navigators(27),doctorsetcthatarrivedperboatfromasinkingislandintheWesthavebeencontainedontheBritishIslesin,forexample,oldlegendsandafewIrishnovels.

Answer: The stories about large groups of gifted musicians, architects, navigators (27) , doctors etc that arrived per boat from a sinking island in the West have been contained on the British Isles in, for example, old legends and a few Irish novels.

Add spaces: DespitethetenuousnessofhisgovernmentLumumbahadgainedpowerandheintendedtouseit.LumumbawasintentuponpreservingthepoliticalstatetheBelgianshadputtogetherfromincompatibletribalgroups.

Answer:
Despite the tenuousness of his government Lumumba had gained power and he intended to use it. Lumumba was intent upon preserving the political state the Belgians had put together from incompatible tribal groups.