1) There were actually two issues at play here. The link submission form did not accept characters with UTF-8 encoding, and the field in the database was not able to store them either. I have corrected both issues in version 5.9.10.3, available shortly. Please update, then deactivate and reactivate to trigger the database update code that will fix the back-end issue.
2) For the thumbnail issue, are you generating the thumbnails in the link editor, or are you displaying thumbnails dynamically on your link page? If displaying dynamically, do you have the option called ‘Give priority to images assigned to links if present’ checked under the Thumbnail tab? Have you ever generated a thumbnail for an image? Do you think that you are getting a robothumb image because a link has an image saying it came from robothumb, or are you see that in the image path when you examine the page source?
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