I didn't notice this the first time, but now I can clearly see that new signals button is completely useless. This is certainly better than looking among the advanced settings, but will be pressed not more than 2-3 times and will be forever forgotten.
If the player knows about the existence of block signals and want to use it, he will permanently turn on the old (extended) menu and completely forget about this button.
If the player does not know about block signals, he will not turn on the old menu and will also forget about this button. Or if he is inquisitive, he will press this button and will… "use block signals incorrectly."
I suggest to show a message asking the player to choose how the signal menu will look and act.
If the player clicks YES, show the old signals menu, which contains all the signals.
If the player clicks NO, the signal menu will be turned off completely. The semaphore / traffic light is selected according to the setting «build semaphores before». The default signal is one-way PBS, changing the signal by ctrl+click on curren signal. (as it was before 12.0 with several settings on it).
About «Signal convert».
A short video in which I trying to use this feature: https://youtu.be/LD3UGMkQ32g
It is also worth applying the mechanics of placing PBS on ordinary block signals.