Fixed activities with multiple revision restores

Fixed activities with multiple revision restores to conform with aggregation rules.

Note: This PR is based on https://github.com/oaeproject/3akai-ux/pull/3820 because of the overlap in i18n keys it touches.
This is done automatically by the synchronisation script (a Node bug when serialising objects), so there is no point in reverting this. The next time we do a synchronisation, this might happen again (elsewhere).