On the same page (6) of the 1841 Census for William Williams is "Gellywrol" and "Tywylym". Checking out the three on tithe map -
1841 Census :- Place - Gellywrol, Occupier - Daniel Jones
Tithe map :- Farm Name - Gellywrol, Occupier - Daniel Davies, Field No. with building 1036, 1039
1841 Census :- Place - Tywylym, Occupier - John Joseph
Tithe map :- Farm Name - Tygwilym, Occupier - John Joseph, Field No. with building 1018
1841 Census :- Place - Glanrafon, Occupier William Wms
Tithe map :- Farm Name - Glanyrafon, Occupier William Williams, Field No. with building 974
This link should take you to the Tithe map and field nos.
https://places.library.wales/viewer/4644161#?cv=&h=974&xywh=15554%2C13128%2C1804%2C961
The building on field no 974 might not be a family dwelling (the field name is Cae War Ty) but its location close to Nant Eiddig would make Glanyrafon more than appropriate.
You can see Gelli-wrol and Ty-Gwilym on the 1887 map previously posted. Also note the variations in spelling of the place names.
Good luck
Thank you very much hanes teulu for your research !
