No you would not lose existing events if you reinstall the plugin.

I believe you that you have this problem but I cannot debug individual sites. If you track down the problem please post the solution here and or in github and I will patch the code.

I don't know how or where to change the time code. It seems for me that the real solution would be to be able to set GMT or country in the options.

I'll check often if someone finds a solution.

Thanks.

Solved:

Edited .htaccess document in elgg's main installation folder.

Added "SetEnv TZ Europe/Madrid" at the very top of the document. (In this case Madrid is my timezone as I'm in Spain).

Listo!

It is weird as my server's time is the same, so this souldn't be necessary. But techs are sometimes a mistery.

Salud.