I did a cursory look and the 34450A seems to share some aspects of the 34405A such as the locations of the rear USB, power and ground locations and some front panel layout cues. Many of the 34405A units have a label that states they are made in Taiwan, although some do say made in Malaysia. HighVoltage posted in another thread that the 34405A was not an Agilent design, but provided nothing further and I didn't dig much more than that. So it's reasonable that the 34405A/34450A came from another company and perhaps some units were initially manufactured by that company, but eventually all manufacturing was moved to Agilent/Keysight's factories in Malaysia with some money changing hands in the process. Maybe B&K Precision or Picotest, or one of their subcontractors.
Given that this is a 5.5 digit DMM, I don't see there being an issue with where the design came from or originally made it. You're not going to need deep design history to make it work well enough.
The large display is great if you need to read it from across the street, and some of the other uses of the display are somewhat interesting with regard to the statistics and dual display.
However, I had considered the 34450A in the past but the OLED display concerned me a little bit. It can suffer from burn-in as well as dimming over time. Ultimately I snagged a 34461A when a deal came up. The current Keysight promo on the 34465A is pretty good if you can afford the extra spend. As I mentioned in another thread, the best option for that promo is to get the U1733C as the free item, although I'm not sure how that all works if you're not in the US.