Libraries can help and encourage their communities to participate in Wikipedia editing and translation in many ways as follows:
In this workshops, there could be a way of community interactions, having fun, suggesting specific subjects and themes, and creating discussion and editing groups.
Marketing these workshops could be done through social media links and use of fliers and interacting with all kinds of libraries.
Online training and communication is a very important process. Libraries can present online sessions for users, contact them and share these sessions on social media, follow up and contact the interested users. It could be presented as one session, series of sessions, or a MOOC.
This sessions could be used later as kind of flipped classroom, where users could meet after watching the sessions and apply what they have learned in a classroom, and under supervision of an expert.
Conferences:
A one day conference, where users of Wikipedia can meet, know their peers, enjoy their works, get motivation and appreciation for what they do is a good add for the work. That could be financed by the users and supported by volunteers.