[morzh]

Forgot to add: I decided to see if my tweeters were connected counter-phase as expected. When disconnecting them, I labeled the wires, so when reassembling them on the workbench I used the original wires sequence.
The speakers wired left-to-right as 3-4, 3-4.
Now if they were counter-phase, the wires that connect them in series (that are essentially 1 wire and are ohmed out as near-zero ohm) would go to the same pins on both speakers; but they went to the different pins.
So if you imagine one over the other, the pins would be wired as "Z" letter, that is the GND going, say, on pin 4 of the first speaker, then the wires connecting the speakers in series go to pins 3 of the first one and to the pin 4 of the other, and then the transformer wire (top one on the sch) goes to the pin 3 of the other speaker.
So everything was OK; whether because of someone corrected that in the past (yes as I said before, the radio was repaired some time in 1950s I guess) or it was wired right from the beginning.

PS. My capacitor initially was 1.5uF and as I said, the tweeters were not that noticeable. I parallelled another 2.2uF cap, making the total capacitance 3.7uF (vs 1uF original) - now they are quite noticeable.