Pretty decent slice-of-life base-building, I rate it as 7.5, rounded down for now.
It's cool and all, watching a mountain region be developed, but because she brute-forces every problem with Saintess power and her reality-bending tablet, there's nothing really relevant or interesting about it. Like, there's nothing in it that I can use for my own landscaping, y'know? No little tidbits about how real-world mountain landscaping actually works? No conflict resolution or philosophical thoughts.
And OK, so she was a Saintess in her previous life, but what's compelling about the character now?
If this mountain were to instead be given to, say, Kaoru Nagase from I Shall Survive Using Potions, I'm sure she would do something interesting and funny with it...
BTW, I tried checking out the web novel version, but the manga is already past the (free) translation.