If you enter into your weorian Strong hold and then lost arts you will see three types of Lost Arts upgrades that that can be done for weorian units the one in the center is the one that upgrades the build times as you increase them the units will take a shorter time to be built. I hope this is the answer you were seeking 

 Or it could be the settings On your Brigadier Champion they will have a noticeable effect on your stoneheart build times  

ALCOs Rule said:

Hi there - what elements make up the Stoneheart Production Times.

The Weorian Stronghold has a bonus, but it seems that there are other factors involved when comparing production times with other members in the league.

https://prnt.sc/tz0bgt

Thanks for your input.

Quick clarification:  Weorian units are NOT affected by stoneheart build speed bonuses.  

The things that affect build time of your stoneheart units are: 

-Level of the weorian stronghold: max of 30% training speed boost.  

-Training speed boost item: 50% training speed boost

-Brigadier champ (must be equipped in your stoneheart castle section in champion menu): max of about 150% boost for enlightened and fully orbed grade V at 7 stars

These all boost the base training speed, so with all these bonuses you can get training speed up to about 3.3x the base value, resulting in a 70% reduction in training time for a particular unit.