Once the new script is ready, we'll want to test the new ICU library numerical sorting.
The first test will be on testwiki, and after that, it would be good to start with some smaller wikis and work our way up.
The next step up from testwiki might be one of the Wikitionary sites that Johan's been talking to.
Some Wikipedias are already using the ICU library, but not using the numerical sorting. Switching to ICU numerical sorting on those will be lower-risk, because it's less of a change. The wikis that currently use ICU library include: Swedish, French, Dutch, Russian, Polish, Finnish, Portuguese, Persian.
For this task: Identify and check in with a few communities who are interested in being an early adopter for numerical sorting.