Oh My Goods!
Is there a 2.0 rulebook newer than v1.5, and which rules version is current?
No. The current official English rules are v1.5 on the publisher's (Lookout) site, and the designer confirms they are the latest. The "2.0" label refers to the revised rules, which v1.5 already contains; there is no separate newer rulebook. A quick check is that your rules let you use all production chains in the last round.