Way back in 2015, in the dying days of Senior Railcards enabling off-peak tickets on early M-F northbound (then) VT WCML services, I travelled Watford to Piccadilly and had a day in Lancashire using a Lancashire Day Ranger. I was a bit late arriving at Lime Street and just missed a Chat Moss train across to Piccadilly to catch the Pendolino back down south. I saw that there was an EMT Norwich service leaving soon so I went to the Northern Booking office, showed them my Ranger and asked for a single ticket to Manchester. They insisted that my Lancashire Ranger was valid on the CLC line* and said that I didn't need to buy another ticket. Despite me questioning that, they reiterated that it was OK. So I got on the EMT train which was crowded to standing. Some way into the journey the guard passed through so I put the ticket and my Senior card on the table and looked away out of the window. He gave it a nod and a 'thank you' so it was back in my pocket asap. I saved about £8 or £9 but wouldn't have been very happy having to convince a guard that the booking office thought that it was valid.I think that this has been highlighted before as being confusing for passengers. The Lancashire Day Ranger is only valid between Liverpool and Manchester (the two big cities in the old county of Lancashire) via Earlestown, and not via Warrington.
The extended version of the Ffestiniog Round Robin is actually available from stations a little beyond Liverpool/Manchester/Birmingham that you would never know about if you relied on the official validity map e.g. Hightown.
* The most southerly line that the Lancashire Ranger is valid on is the Chat Moss. The Cheshire Ranger is valid on both the Chat Moss and the CLC.