Rathvilly RC parish covered parts of Wicklow and Carlow in its service area. From looking at the baptismal record on the subscription site Roots Ireland, the Dowling family lived in Ballyhacket townland in Kineagh civil parish in Co. Carlow. There was/is a Ballyhacket Lower and Upper.
Other siblings Mary 1822 Michael 1824 Catherine 1826 John 1830 NOTE all four of these records show Bridget/Biddy Darby or Bridget McDarby but I believe this is the same person shown as Judith. Address was Ballyhacket.
I did not find a marriage record for John Dowling and Bridget/Judith Darby.
The Griffiths Valuation head of household listing for Kineagh parish from the early 1850s does show a John Dowling in Ballyhacket Lower townland. https://www.failteromhat.com/griffiths/carlow/kineagh.php
I did not find a John Dowling baptismal record in Rathvilly parish around 1800.