The following is a list of strings that are either not on Transifex to be translated, or that are on Transifex and translated and don't show up in my (Dutch) translation in beta. The actual strings are between quotation marks. I'll add to this list if I find more.

http://beta.musicbrainz.org/
"Read more »" Under MusicBrainz Blog to the right

http://beta.musicbrainz.org/release/add
"Type to search, or paste an MBID" in the fields for Artist, Release Group and Label
"Add link:"
"« Previous"
"Next »"
"Some errors were detected in the data you've entered. Click on the tabs shaded red and correct any visible errors." on the edit note tab
"Change all artists on this release that match "

""

http://beta.musicbrainz.org/artist/create
"Began:"
"Begin area"
"Ended"
"This artist has ended."
"Born:"
"Born in:"
"Died:"
"This person is deceased."
"Died in"
"Type to search, or paste an MBID" in various fields

http://beta.musicbrainz.org/release-group/create and http://beta.musicbrainz.org/label/create and http://beta.musicbrainz.org/recording/create and http://beta.musicbrainz.org/place/create
"Type to search, or paste an MBID" in various fields

In the "add relationship" pop-up on create/edit object pages
The object types in the drop-down list.
"Required field"
"Change all relationship credits for

on the page."