WordPress 3.5

I’m working in a project using WordPress, and in the middle, updated WP to 3.5 version. My child-template stopped to work, and I realized
the translate is brazillian portuguese, but it apparently has parts in Portugal portuguese and in english.
I like to suggest a revision in this version and in brazillian portuguese translation.
There is some way to back one version in a installed WP? This feature would be useful for disaster recovery (like that I describe here).
I ask that you forgive me the frankness, but delete WP and database and re-install all is something very nuisance when you got a job to deliver.
TYhanks for attention.