No. Other data on your phone will not be influenced. The program is completely read-only software for WhatsApp. When you restore the WhatsApp backup to your device, only the original WhatsApp data on the target device will be erased. Thus, all your operations merely make a difference on WhatsApp. It won't modify other data on your phone.
What's more, your data is 100% secure. There is no other software attached to it. FonePaw WhatsApp Transfer for iOS won't keep and leak any data on your device or in the backup file. We take your personal data and account seriously. You're always the only person who can access it. We also offer backup encryption to guard your privacy.