Beautiful build!
As far as the routing through the handlebars goes, yeah, it seems most of the integrated bars from China are not the easiest to route. I found that the issue isn't necessarily that the cables cannot be routed without some damage to the housings. As far as I can tell from my own experience, it's all cosmetic and the internal structure of hydraulic lines or mechanical shifting remains intact and working. They just don't work great without some really precise orientation through the bars, headset, and headtube. Any deviation from your cable/hose orientation at one spot will have knock on effects every place else. It's not so much the 90 degree bends in the cables and hoses themselves that cause most of the issue. It's any of the lines crossing over through the bars, stem, headset, and even the head tube to a certain extent, that cause pinch points that collapse the lines. Those pinch points make it difficult to route through the lock ring and all those tight spaces along the course of the routing.
Luckily, it is workable and even if you had pinch points initially, once you get rid of them, the lines are still able to function as intended. Hate to say it, but it's just one of those things that has to be managed when you are dealing with open moulds.
