I have just managed to get my service status active via the help of yourselves, however it still appears that the node service is not actually running.

So put simply, I know my node app is running, but for all intensive purposes, it isn't acting as it should.

Service status

root@server:/etc/systemd/system# systemctl status parsoid.service 
● parsoid.service - MediaWiki Parsoid Server
 Loaded: loaded (/etc/systemd/system/parsoid.service; enabled; vendor preset: enabled)
 Active: active (running) since Sat 2018-12-15 21:18:06 GMT; 29s ago
 Main PID: 18799 (node)
 Tasks: 9
 Memory: 34.8M
 CPU: 1.449s
 CGroup: /system.slice/parsoid.service
 └─18799 /usr/bin/node /var/www/gwart/mediawiki/extensions/VisualEditor/parsoid/bin/server.js

Dec 15 21:18:06 server.live-servers.net systemd[1]: Started MediaWiki Parsoid Server.
Dec 15 21:18:07 server.live-servers.net node[18799]: "name":"parsoid","hostname":"server.live-servers.net","pid":18799,"level":30,"levelPath":"info/service-runner","msg":"master(18799) initializing 2 workers","time":"2018-12-15T21:18:07.189Z","v":0
Dec 15 21:18:07 server.live-servers.net node[18799]: "name":"parsoid","hostname":"server.live-servers.net","pid":18811,"level":60,"moduleName":"lib/index.js","levelPath":"fatal/service-runner/worker","msg":"Unexpected token ...","time":"2018-12-15T21:18:07.898Z","v":0
Dec 15 21:18:08 server.live-servers.net node[18799]: {"name":"parsoid","hostname":"server.live-servers.net","pid":18799,"level":40,"message":"first worker died during startup, continue startup","worker_pid":18811,"exit_code":1,"startup_attempt":1,"levelPath":"warn/service-runner/master","msg
Dec 15 21:18:09 server.live-servers.net systemd[1]: Started MediaWiki Parsoid Server.
lines 1-15/15 (END)

Looking for the port 8000

root@server:/etc/systemd/system# netstat -tulpn | grep 8000
root@server:/etc/systemd/system# 

However I can see that the node application is running

root@server:/etc/systemd/system# ps ax | grep node
18799 ? Ssl 0:00 /usr/bin/node /var/www/gwart/mediawiki/extensions/VisualEditor/parsoid/bin/server.js
20820 pts/1 S+ 0:00 grep --color=auto node

Service file

[Unit]
Description=MediaWiki Parsoid Server

[Service]
ExecStart=/usr/bin/node /var/www/gwart/mediawiki/extensions/VisualEditor/parsoid/bin/server.js
Restart=always
User=root
Group=root
Environment=PATH=/usr/bin/node:/usr/local/bin
StandardOutput=syslog
StandardError=syslog
WorkingDirectory=/var/www/gwart/mediawiki/extensions/VisualEditor/parsoid

[Install]
WantedBy=multi-user.target

I believe it is related to this question:
Starting node application with node works but not when starting it with /usr/bin/node

/usr/bin/node seems to be the node executeable installed by the package manager and too old(v4.2.6) for parsoid.

The command node worked here because that command was linked to /root/.nvm/versions/node/v6.7.0/bin/node installed by nvm running v6.7.0.

To fix this, create a symlink to your current nvm version (in order to able to easily adjust when you update) and use that path in your .service file.

Note:
I wouldn't recommand deleting the symlink or file /usr/bin/node in order to place a symlink with that name there, as that might interfere withe the "stock" node installation.