The new Titanium recipes are now available in version 1.7.0.
I couldn't fully understand your balance suggestion with the 15:5 ratio. The titanium-in-foundry recipe and ratio are original from Brevven. Therefore, the titanium-in-foundry recipe remains unchanged (2->1).
The crushed-titanium-smelting ratio also follows its uncrushed recipe (10->2,5 with K2SO and 10->1 without K2SO).
I think I've found a suitable solution for the enriched-titanium-in-foundry recipe that also includes your suggestion with the vacuum and the K2 advanced furnace:
The enriched-titanium-in-foundry recipe has the same ratio as the other enriched molten recipes (with doubled ingredients). So, the vacuum recipe with enriched titanium is overall the best. Then you can choose to use it with the foundry or the K2 advanced furnace.