Too many layers of the wrong stuff to suit me.
But first, let's clarify the joist structure. You indicate you have 4x10" joists. What it the type of wood, the spacing, and the unsupported span of the joists?
For the subflooring, the MIA requires two layers of plywood or OSB, properly installed, for subflooring under a natural stone installation.
On top of that there must also be a proper tiling substrate of some kind. It can be a fiber/cement board like Hardibacker, any of a number of other CBUs, or an uncoupling or crack isolation membrane. You gotta have one of'em.
Without knowing just what it is you're calling "flakeboard," but even if it's OSB I say it's gotta come up, along with the pine flooring.
The original board subflooring, if in good condition, can remain and be topped with a minimum of half-inch plywood, depending upon the spacing of your joists.
There is no requirement for a vapor barrier anywhere in that subfloor package as far as tile installation is concerned. If you have a moisture problem it should be dealt with in the crawl space or basement or whatever else might be below your floor.
Not what you wanna hear, I know, but that would be my recommendation.
My opinion; worth price charged.