Speech is recorded only for the purpose of allowing you to state your inputs instead of typing them. The speech is sent to Google for the Speech to Text conversion, and BPBliss simply extracts the values for your data input. Recording happens only when the screen displays a microphone full screen, and prompts for what input is needed.
The only Google Sheet that is updated is the one you explicitly identify as your data output sheet.
Two sheets are read. The above named data output sheet, and a template sheet you explicitly name for the starting state of a newly created explicitly named result data sheet.
A Google Calendar is optionally updated with an abbreviated format of the same data that goes into the Sheet. It is recommended that you set up a special calendar in Google Calendars for this purpose so that you normal event data is not mixed in with you BP data. Only the explicity identified calendar is updated, and nothing is read or removed from any calendar.
When the data is stored in a Google Sheet and optionally a Google Calendar access to the data is controlled by who has access to your account.
By using the sharing options provided in Sheets and Calendar you can optionally provide access to your data to others that you explicitly identify, or is the case of a public link to anyone with the link.
The ultimate security and privacy of your data is determined by Google policies regarding Google Calendar, Google Drive, and Google Sheets documents.