Thanks for the report. Fixed the locale tooltips but I'll release the update later.
With cliffs, I can't think of a good solution how to implement it at the moment. It would be manual fixing either way. Now you cancel cliff destruction and miner construction. Or you then you'd have to manually fix what a layout missed because of cliffs.
Appreciate the info, it's simple enough to cancel the decon for cliffs once the rest of the layout is placed. I'm also running into issues with the "sparse" layout and poles with a long reach. You should be able to reproduce it with omnicompression and selecting a compact wooden electric pole.
Here's an image of the layout the planner placed, nothing blocking the construction: https://i.imgur.com/lcOo8iV.png
The supply area is each pole is 14x14, enough to reach two miners at a time.
Here's a saved game with the issue reproduced: https://files.catbox.moe/uzqluj.zip
You can either rename the file to MiningPatchPlanner-BugReport.zip
or extract the zip to your saves folder.