To come back to a map you need to save its permalink. If you use the Arcana version of the generator, you can copy it right from the browser's address bar, otherwise, choose "Permalink..." in the context menu. As with my other generators, most manual changes made to a map are not saved in its permalink, but since there is not much to change in Perilous Shores, it's less of a problem here than in the city generator.
The thing with dungeon names is a known flaw of the integration of these two generators. When a dungeon is opened from Perilous Shores, a random dungeon with a random name is generated (but always the same for a given cell on a given map) and only the title of its map is changed to match the name in Perilous Shores. This will be fixed later.