Fay:
Welcome to Ireland Reaching Out!
I checked on Roots Ireland and the only George Howden marriage was in 1835 in the Clonbroney Co. Longford C of I church to an Elizabeth Wilson. Since the Peter Robinson settlers left in the 1820s, I assume this record is not for your ancestors. Here is a link to a Facebook page on the Peter Robinson settlers https://www.facebook.com/groups/585781828107292/
Roger McDonnell