Well, reached last goal of part 4 ) part 4 goal 6) . And what is required to upgrade Gnomish mine to level 10:
The reward Gnome is called Poppy - she has 4 h timer ( 16 gem to speed up).
Here is her inventory card:
After you upgrade mine to level 10 - all Gnomish Forge crafts go away:
Plot L3 Did become available - but I had to force close the game to be able to expand there.