I just noticed that the voukoderplug.dll file did not appear in the FileIO Plugins folder in Vegas Pro 14, but it DID appear in version 15 (which I uninstalled due to performance issues), so I had to copy that .dll file to C:\Program Files\VEGAS\VEGAS Pro 14. 0\FileIO Plug-Ins\voukoderplug\, as well as the Voukoder-x64.fio2007-config file in C:\Program Files\VEGAS\VEGAS Pro 14.0\, and it actually worked.
I did some testing with the Voukoder settings, such as changing it to “very fast” and also the H.264 (AMD AMF) codec, and I did notice an improvement in export speed in Vegas Pro 14 compared to the default settings, even with a low-end laptop.
Thank you Joe24 for your help.