BuddyPress.org

Starting with group slug problem:

https://buddypress.org/forums/topic/group-slugs-when-i18n-environment

BuddyPress should offer options to set group url (slug) to be %postname% or %post_id%. Otherwise they should add a new text field to edit group slug upon creation of groups.

Next is activity excerpts bug:

https://trac.buddypress.org/ticket/654

Once it was fixed with 1.0 series, now it happens again on 1.1

If you have technical skills to submit patches on these, please do so. I may be able to help you find bits of code, but I can’t write anything from scratch.