The calibre admins are listed at the bottom of the calibre forum, but the following are no longer active -- Starson17, Piper_, GRiker, Manichean, kiwidude, ldolse, user_none.
I think you need to find a distinctive icon. The Preferences->Look and Feel->Show text under icons setting has a 'Never' option, when that was used your plugin icon would indistinguishable from the 'Choose library' icon.
BR
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