I have successfully installed and run both accountsservice 0.6.35-0ubuntu7.2 from trusty-proposed and accountsservice 0.6.37-1ubuntu10.1 from vivid-proposed. Querying accountsservice for language and regional formats seems to work as expected, and even if I haven't measured it, the desired performance improvement requested by the bug reporter has most likely been achieved.
I have successfully installed and run both accountsservice 0.6.35-0ubuntu7.2 from trusty-proposed and accountsservice 0.6.37-1ubuntu10.1 from vivid-proposed. Querying accountsservice for language and regional formats seems to work as expected, and even if I haven't measured it, the desired performance improvement requested by the bug reporter has most likely been achieved.