I have been making all the research items in equal amounts without using most of them and I have just noticed that Tomes now need 2 Manuscripts each and Codex need 2 Tomes per codex. Is this a bug due to the gold requirements going up for Manuscripts?
I can understand the other resources requirements going up slightly over time, but I think the Manuscript and Tome requirements should never go higher than 1, it just ends up requiring far too much time if 1 Codex suddenly needs 4 Manuscripts and 2 Tomes to produce (and maybe 9 manuscripts and 3 tomes later)