Thank you for your message.
I cannot find any reference to a Ballytaggan in Tyrone. I wonder was the name misheard and taken down incorrectly, or transcribed from another source incorrectly? There are some townlands in Tyrone which sound similar, eg. Ballyhallaghan, Ballylagan.
There is also a Ballytaggart in Antrim.
You can see a list of townlands in Tyrone here:
Perhaps it may be an idea to contact a library in Tyrone for some more information. Here is the contact information:
Library Service, 1 Spillars Place
Omagh BT78 1HL
(028) 82 244821,
(028) 8224 6716
Catalogue online: http://opac.ni-libraries.net/
Hopefully they may be able to shed some light on this place name for you.