When I was a child in the early 70's, the JWs were saying the earth was older than 6,000 years. They said creative days were figurative. They could be much longer. I thought I grew up with 6000 years, maybe it was 7000. But the reason for limiting it there is obviously to make a nice 7 day week.
6 days of creation, a day of rest, then armageddon and paradise. The assumption being that the time from "the fall" to the "new world" was also the length of a creative day. Get away from that and say creative days were several millions or even billions of years long and you can at least sidestep some of the obvoius contradictions with science.
Haven't read anything recent, but they may be trying to keep mum on the details. Setting numbers always gets them in trouble. Whether it's lengths of creation days, the length of the "Gentile Times", 6000 years of man's existence ending in 1975, or the length of a generation. Just be more vague.
And I've never met a JW who thinks the tall tales mentioned in the bible didn't happen.