Modifying USB 2.0 Hub to use an upstream Type C connector won't communicate Data
There are two fundamental problems with this re-work:


You cannot use "speaker wires" to transfer USB signals. If anything, you should use a piece of standard USB cable for this. USB data lines must have 90 Ohm (+- 15%) differential impedance to work properly. You can't debug this and the only solution is to use proper USB 2.0 cable (which has D+/D- as a shielded twisted pair), and make soldering ends as short as possible.
You cannot "split" the connection and keep your old cable. It means that you need to cut off your old cable, you can't have a fork on USB data lines. Hanging ends of cable will produce horrible signal reflections, and USB doesn't like it at all.


To debug the USB connectivity issues you need a USB protocol analyzer, something like Teledyne-Lecroy Mercury T2, or Total Phase Beagle 480, or Ellisys Explorer 260, which run for $500-$1000, or maybe some cheaper clones from Alibaba or eBay.