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Simon is correct, there's no benefit to a 301 with domains that have no established web site or domain authority which it appears these two do not. I would definitely 301 them to their respective language's landing page.

It would be a shorter url (good), and a more descriptive page name (good), but your original one isn't bad either (no dynamic variables and etc). If your currents structure is already being indexed, I don't think it is worth changing though.

Hi Remco, I think your instinct is correct here. You could set up a campaign for each language subfolder, which would allow you to choose keywords, track rankings, and optimize content for each language individually. This would also create targeted crawls for each language directory.