I’m unable to find any concrete license details for Local on this site or in the app itself, which could be an oversight on my end. When they have been asked what their license is, they say it’s proprietary without providing any further details.
Everything may very well be GPL kosher, but they should have details of their own license on their site, in the app, or available when requested. They need to provide more details than stating “it’s proprietary” when asked.
The license should specify which parts of the app are proprietary, and what restrictions there are on those parts.