Will non-US number formats impact data collection?

No. iPad settings that are configured to non-US regions will not impact data collection. The data will be collected using US format, even if the iPad is configured to a non-US region. The data is presented by the app with the format selected from within the app (which may be different than the iPad setting). Users can select date and number formats used in reports, exports, audit logs, and in the shell UI (app screens). By default, dates and numbers for all users will be formatted in US format. Numbers and dates will only be presented differently if they are changed from the default formats by the user, in the Settings screen of the app.