The new version (v2) of Content translation became the only one to translate new articles. So version 1 is only used when editing translations started long time ago. Since old translations are discarded automatically (T183890), at some point CX1 would no longer be reachable by users and the CX1 codebase can be removed.
Since there are may be common parts between CX1 and CX2 we need to be careful not to affect CX2 with this clean-up.