I'm playing as Atronach and i cant absorb spell from Lucky Old Lady statue, also it seems like i have very low chance to absorb any spell from enemy, is it made on purpose? And can i use tweak that was made by kind person from nexus forum or it will couse bugs?

I don't know what tweak you are referring to from NEXUS, but the answer to your question is yes, the UOP team considered it a bug and fixed it so the atronach no longer absorbs blessings from alters or the Lady Luck statute.

Hm, its gonna bring more challange then...

It is not much of an extra challenge with magika on using the Atronach sign. There are many ways to get magika back like eating some ingredients that are plentiful to find, creating magika potions, and go hunting for some nice stones in some Ruins.