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this answer this answer on StackOverflow. Or consider making a donation. You can also migrate the layout to other Linux distributions. In case you had, please let me know so I can make these packages available to public.
Currently I spend most of my time finding an appartment in Berlin-Kreuzberg. Contact me if you know something.
Check this link: http://superuser.com/a/171162/384610 (it's for Windows XP but works for Windows 10 as well)
Make sure the key isn't configured as hot-key in your operating system. KeePass 2 uses ALT_GR + A for 'Global auto-type'. See https://superuser.com/a/553138/384610 for how to disable this hot-key.
Please contact me and I'll try to find out the problem. In the meantime, you may have a look at this answer: https://askubuntu.com/questions/482678/how-to-add-a-new-keyboard-layout-custom-keyboard-layout-definition/483026#483026.
For Windows, I created a registry file that maps the Insert key to AltGr. Making manual changes to the registry may damage your Windows installation. So if you know exactly what you are doing, and you know how to remove registry entries, you can try out the mapping. Here's to acitvate it, InsertToAltGr.reg, and here's to remove it, RemoveKeyMappings.reg. Again, only run it after having verified the registry files do what you want.