If you really want to fix the serial comms, we can help. Post a schematic of your wiring. Post your code for the NodeMCU and the Uno. Tell us what your code actually does and how that is different from what you want. Read the forum guidelines to see how to properly post code and some good information on making a good post.
Use the IDE autoformat tool (ctrl-t or Tools, Auto format) before posting code in code tags.
The serial input basics tutorial may have information that you can use.
But, in the end, I would use external components, not another processor.