With 79bc453 a suitable keyboard image for legacy keymap style was substituted with an image that works for 42style. In turn the 42style image is also wrong.
It may turn out that proper images were already made by @c3d, but a mismatch occured during commit. So for now I would not invest time to create a legacy keyboard image with σ as ALPHA-input of yellow-shift-E key.
See also my MoHPC forum post for a workaround, if you are '42style user'.