I’ve afraid there isn’t a enc-converters package available for Xenial/16.04.
In the past Paratext has always used the enc-converters package, which was actually a problem as it conflicted with the fieldworks-enc-converters package (which meant that one couldn’t have fieldworks installed and enc-conveters at the same time)
Give the unavailability of enc-converters, and the conflict problem, it likely makes sense to switch paratext to using the fieldworks-enc-converters package.
If you are happy using a terminal/command line you can actually do this manually (until an updated PT package with this change is avaliable):
Switch Paratext to use fieldworks-enc-converters.
Assuming fieldworks-enc-converters package is installed.
(if you haven’t already) Start Paratext once on the system then close it.
In a terminal:
cd ~/.config/paratext/registry/LocalMachine/software
gedit sil/silencconverters40/values.xml
Replace the entire file this:
<values>
<value name="RootDir"
type="string">/usr/lib/fieldworks</value>
<value name="PluginDir"
type="string">/usr/lib/fieldworks/EC/Plugins</value>
<value name="DeveloperPluginDir"
type="string">/usr/lib/fieldworks/EC/Plugins</value>
</values>
(of the contents of this pastebin https://pastebin.com/9ADbnGY9)
Save file and close gedit.
mkdir wow6432node
cp -R sil wow6432node/
#########
Please note the encoding converters Help/About tab did not display correctly when I did this. (Possibly because I lacked some FW package)