When the change is applied on each Wikipedia?

Wikimedia Wikis are generally updated weekly, but there are delays during some holidays, as not enough administrators to validate the imports and look at commits, test them and answer rapidly to issues. Your update on 27 December is not so old, there are just a few additional days to wait for (and even when they come back there may be some more urgent things to work on before applying updates in many wikis).

May be your update is already visible in some major wikis in Tier 1 (such as Commons). And not all updats are necessarily applied at the same time for all modules (notably if there are some blocking dependencies before merging changes using these updated texts with possible conflicts from other pending branches that admins have in priority). You may look at Task lists on Phabricator's board for such updates... Nothing is forgotten, and certainly not for the Visual Editor and the Growsth Experiment which are very active and have plenty on ongoing changes.