No because <Primary>-<Equal> would be very uncomfortable on my German keyboard layout!
Seriously, I understand the point and that the equal sign is easier to type than the plus on a US keyboard layout. Interestingly, on a German layout it's vice versa.
Regardless, what I'm wondering about and what I don't understand is that the Gnome HIGs suggest <Primary>-<Plus> (https://developer.gnome.org/hig/reference/keyboard.html?highlight=zoom#view-...). And I guess this is also where the current default value in Geany has its source.
Until this PR I wasn't aware of <Primary>-<Equal> for zoom in. But just noticed Firefox (at least in my configuration) accepts <Primary>-<Equal> *and* <Primary>-<Plus> for zoom in.