Further issues with TACA, I attempted to book some domestic flights with them a few months ago LIM-CUZ.
They had a great business class fare for sale on their website and ITA software.
But when it came to book, it was impossible to book these fares. The website displayed code errors at the payment screen.
I contacted their help desk for assistance. The live chat was never working and by the time the web team got back to me (72 hrs) I had moved on to another airline (LAN Peru).
I fear that you may be chasing fares that may never be able to be bookable.