It's been some time, but I wished to thank you all for your suggestions.
I read, thought, re-read, and then found the courage to get again 100% on trying.
And all of a sudden, I started getting most of my foiling heel-to-toeside tacks.
It happened few days ago: all of a sudden, they started to succeed, and I was *flabbergasted*!
(of course, the same day my buddy performed his very firsts toe-to-heelside foiling tacks... my pride was short lived!
What changed it all for me were 4 things:
1) keep *both* hands on the bar, which, for now, is essential to me.
In this way it is much, much easier to "look under the armpit", which I finally understood as the key movement to initiate unit turn.
When I try with one hand only, it's a mess... I do not manouver the kite at the zenith and then on the other side. I just leave it at 1', preventing any turn... and I realize this only if I look at the kite!
Two hands, for some reason the kite does exactly what it's supposed to do (more or less...
2) understand tacks are more physical than gybes.
The need to recover body position after turning is something very different from those lazy gybes with zero physical commitment. I was not prepared for the need to be physical during tacks, especially at this point when they are mechanical rather than intuitive. Raising from the tilted position of the carve to get ready for a kite lurch on toeside requires some working with my 100+Kg
3) accept few of them go straight upwind, and most do a fraction of downwind: when tacks don't come out clean, I just accept to go downwind for an instant when diving hard the kite not to fall from foiling
Probably not the cleanest tacks, but they work for now
4) carving is fun, but tacks come out better if I lose as little speed possible. Thus a larger turn means coming out with more speed, and more time to dive the kite. This is not what I see everyone try!
Now, right foot forward I just carve aggressively, and the movement feels just natural, with zero downwind... but left foot forward has been a mess to fix; for now, I do *not* carve, rather I get the kite at the zenith, and turn while being vertical with the body.
I also need to go downwind some, until I can work the kite for a sudden pull. Eventually it works: much uglier than on the other side, but it works, and in foiling
And lastly, these tacks have a bonus included: if you fail them, you can loop and get a 360 without falling down!
So: thank you all, really!
Next steps: refine those ugly tacks, and then go for the toeside-to-heelside, and do not lose the arms race with my foiling buddy!