Important to wisssen - autofocus in low light conditions!

In my a7mk2 I have unfortunately learned that (combined with diffuse light from outside artificially illuminated Church), the focusing accuracy decreases greatly especially in diffuse, low light once. On low-contrast objects such as a child's face is focused.
We have tested the lenses SEL18200 and SEL55z.
Although the latter yielded less waste, but compared to my older a65 I must criticize that these put under the same conditions, no focus problems of the day.
In another, similar test position, the Sony A7mk2 had unlike the Nikon D750, in a shaded area, often struggling with autofocus problems. Where the D750 still Ruck Zuck focused, did not make it the A7mk2 often. Too bad, because I would have been aware that before buying, I would have made it with other considerations. Thus, the acquisition was a little sobering.
Therefore, buyers should be aware that they are particularly with the A7 series purchase the reqired another / younger autofocus technology, which is unfortunately still, under certain conditions, against the autofocus systems' old fashion SLR cameras, inferior.
Meanwhile, I have read of this problem has often in the Internet and you have to be clear that the a7mk2 in bright light delivers a truly excellent overall image quality sets us a good smoke behavior on the day, but in poorly lit, low contrast scenes, not the yellow of the egg is.
If enough time is available, of course helps the manual post-focusing, which works with the A7mk2, relatively well with a little practice.
Thus, I still hope to a firmware update, which will someday eliminate this problem and trust in my still upgradeable manual Fokussierkünste.
Think this is important to know.
Schöen Greetings Günter