At first I thought perhaps that your piano had not been tuned for quite a long time, but then you did clarify by saying it was the 4th tuning in 3 months.
As I recall, the YouTube sample of this piano consisted of single notes, no chords, octaves, double notes - so it's hard to evaluate the quality/condition of the tuning. That said, at least to my ears, the unisons wobbled a bit more than I would find acceptable after a recent tuning unless there had been a LOT of hard playing done on it.
Maybe I'm dead wrong, (and it wouldn't be the first time) but looking at the damper blocks it seems like the damper felt is new which makes me wonder if the hammers are also not original and somewhat recently replaced? The other reason that suggests to me that the hammers are replaced is that the tone and sustain of the notes as you play them one by one seem to differ substantially, suggesting what Jurgen first mentioned regarding the need of a basic more thorough voicing...
New, or old, I agree that the voicing is uneven. That said, to my ears the zingy sound doesn't sound like a voicing problem.
...This can include hammer squaring to the strings, alignment, manipulation of the hammer felt itself (needling/hardening), addressing the bearing points of the wire at the bridge and upper terminations and so forth.
I agree with newgeneration. Were I a betting man, my bet would be that the zing comes from resonances in the indirectly speaking parts of the strings "...at the bearing points of the wire at the bridge and upper terminations and so forth...". I think it might have something to do with the fact that in the Northern Hemisphere we're in the winter heating season, and the piano is (probably) in a less humid environment than it was previously.
Technically inclined readers, and techs - shouldn't it be fairly easy to test that hypothesis by muting off parts of the strings, pressing down on the bearing points while playing test blows?
Most concert tuners are fantastic technicians, but although I wouldn't go so far to say that you stand in second place to their institutional clients, you might just need to make it clear to him/her that you would prefer and will pay for a much higher level of service. There are times when a technician gets used to working on very high end pianos, and offer the skill and the invoice that matches the high degree of craftsmanship to these institutions. When they then service a traditional upright in a home, they may falsely and/or unknowingly assume the private owner does not expect, (nor would be willing to pay for) their concert services and rates.
"newgeneration" raises a number of very interesting, and, at least to me, disturbing points here. The biggest one in my mind is what constitutes a professional "tuning" of a piano? How long should such a tuning be stable? Under what conditions? In general, people who are professional pianists, are going to stress a tuning more than an amateur, and in a much shorter period of time. This argues that the technician do what is necessary (and here we get into the arcane details of pin setting among other refinements) to tune in a way that maximizes both stability and accuracy. Should there be a two-tiered approach to that - the twenty-five minute once over easy vs the one-hour plus super stable concert tuning? Seems to me that in a world where people are less willing to pay top dollar for services, or are less able due to other constraints, such a bifurcation is inevitable. One tech that I called handled the situation by quoting two different rates - one for a regular tuning, one for a concert (professional pianist's) tuning.
Meanwhile - back to PNO40's piano problems. A good technician should be able to address them. How much that will cost, what the value will be to PNO40 vs the cost is something he will have to determine once the problems have been diagnosed adequately.