Diane,
You ask whether Griffiths is the only guide to Patrick & Ann Rogan’s land. Griffiths is the first comprehensive survey of Ireland that links homes to maps. The tithes list farmers (but not the rest of the households eg labourers, shops, public buildings etc) and they don’t routinely have any maps.
The National Archives in Dublin do have some estate maps but they don’t have comprehensive maps of who was on each piece of land in the early 1800s all across Ireland. Some estate owners did have maps compiled. Not everyone did (it cost money) and some have survived. If you think about landowners like any ordinary business, what do people do with their records? Some think, well the storeroom is full and I don’t need these any more and out they go. Others think this is of historic importance I’ll keep it. And in other cases the records just pile up till the owner dies and a clearance team empties the place. Plus in Ireland, many landowners who had decided their records were of value sent them to the Public Record Office in Dublin for safe keeping, but as you probably know, it was burned down in 1922 during the civil war and they were nearly all lost. Bookaun (Browne) appears to have been owned by Richard Brinkley and Bookaun (Tottenham) by Charles Tottenham. You could get a researcher to see if either of those landlords have records in the National Archives in Dublin, deposited post 1922 obviously. (You could search the catalogue yourself, but if you do find anything, you need to get someone to go in person to look the record up).
Bookaun looks to have been one single townland at the time of the tithes (1833) but by Griffiths (1857) it had been split into Tottenham & Browne. I have attached a list of the tenants of both. Looks as though plot 1 in Tottenham may have been tenanted by a priest. There was no house there, just land only. So he probably lived in the Rectory/parochial house. Since you are apparently struggling to find the relevant maps I have taken a couple of pictures of the map and the Google Earth view of both Bookaun townlands. Tottenham looks to be 1 single farm today.
With regard to exploring the area, it’s only a couple of hundred acres so that could be done on foot. Indeed quite a bit of those townlands don’t have any roads into them anyway. (They’ll be accessible on a tractor but not by car). But you would need a car to get there. There won’t be any public transport on those minor roads. Taxis will be pretty scarce too. There are public roads on 2 sides of the townlands but the only way to see them at close quarters would be on foot.
You ask about trying to get someone to locate where the Carolin farm was. You could try hiring a professional genealogist to see if they can unearth anything in the National Archives but the underlying problem is that map creation at a detailed level hadn’t really started in Ireland when they lived there. Griffiths is the earliest set of records that routinely shows most farms. The Valuation itself dates from 1848 to 1864 depending on whereabouts in Ireland you are searching. The accompanying maps are usually around the 1860s. Prior to that individual landowners may have had a map drawn up, as I mentioned, but most didn’t or they have been lost. Judging by the names that remain from the tithes through to Griffiths Roger & I think your Carolin household was in Bookaun (Browne), and you can probably exclude the farms that remain, though it’s possible they expanded and acquired the land given up by those who left. If you compare the tithes with Griffiths you will see there are fewer farms in Griffiths. People were pouring out of Ireland all through the 1800s especially around the time of the big famine. Those who remained often took over land that had been given up so some farms got a bit bigger.
But unless you can find a map somewhere, no I don’t think anyone is going to be able to tell you exactly where the Carolin farm was. But you will be able to know it was within a certain likely area, comprising 100 acres or so. (Your ancestors left 180 years ago, and I'd be surprised if anyone local will know about their farm today).