The Griffiths on-line maps are not entirely contemporaneous with the valuation records and you do sometimes see minor differences where properties have been split or amalgamated between the one and the other. However it’s unusual for 7 or 8 properties to be missing as appears to be the case here. 12 seems to be the top number but there should be 19 properties in the townland.
You sometimes get townlands with a separate isolated bit some distance away from the main bit. When that happens you usually see it named as “Kilnaclasha (part of)” or similar. Have a look at the general area on the Griffiths maps and see if there is an isolated parcel of land like that with the missing properties. Apart from asking locally, I haven’t any other ideas as to how you would find where the farms might be.