I can see you are using content controls for the "fields". This is a good design choice
You say the user will enter the values in the Word document itself. This is using Word? Are they constrained to eg Word on Windows, or could it be OSX, Android etc? Word Online? An alternative might be https://nativedocuments.com/
(I have an interest there)
With content controls, you can "bind" them. See further https://docs.microsoft.com/en-us/visual ... ew=vs-2017
With data bound content controls, it is easy to extract the data as an XML file. You can then use XML technology to validate.