So if the initial silences don’t occur at completely regular intervals such as every 5 seconds, I suggest you try Steve’s experimental Stretch Silence plug-in which was written for a similar use case to yours.
The plug-in detects silences based on a specified Threshold level and minimum length of silence, then expands each detected silence by a specified length. Put the downloaded NY file in the Audacity “Plug-Ins” folder, then restart Audacity. You will see the plug-in in the bottom part of the Effect Menu.
Use this plug-in first, then Sound Finder to add labels, then Export Multiple.
You could use this plug-in in a Chain, but you don’t need to - you only have two effects to run, and can’t use Export Multiple in a Chain.
Give Steve some feedback about the plug-in, please if you use it.
By the way, the word is “track”, not “tract” for audio meaning.
Gale