HJS apps do not do any network communications or send any data to a server. Any data stored in the apps are solely stored on-device or in backups of the device. There are no third party analytics packages installed in HJS apps.

If you have opted-in to sharing diagnostic data with developers on your device then Apple may share a crash report with me, but that crash report will not contain any of your personal data.

Today Timer can share timers between devices using Apple's Handoff technology, but no data is passed to a external server during that process.