Here is the comment from the email thread indicating it is possible to do this (I'm assuming it would be done in the Integrator Addon):

On 2/17/2016 1:08 PM, Chris <chris@espacenetworks.com> wrote:

On 2/16/2016 8:37 AM, Tanstaafl wrote:

On 2/16/2016 8:12 AM, Christian Mack <christian.mack@uni-konstanz.de> wrote:

Am 15.02.2016 um 14:31 schrieb Laurent Wargon:

Hi all,

With Thunderbird Lightning, event categories are not synchronized with the categories defined in the web interface. Yet contact categories defined in the web interface are synchronized.

Is this normal ?

Yes, that is normal, as calendar categories are managed in Lightning,
which does know nothing about SOGo.
But remote Adressbooks are managed via SOGo Connector Add-On, which was
created specifically for SOGo, therefore knowing how to get those
categories.
So, is it possible, with some coding/enhancement to SOGo Integrator that
SOGo could become are of/manage Calendar Categories? Or would this
require some change/enhancement to Lightning?

Yes there's a javascript API which would let SOGo integrator obtain the
calendar categories of calendar events.

See the code in this add-on, the Provider for Google Calendar, allows
bidirectional sync of google calendar events with thunderbird lightning
calendar:
https://addons.mozilla.org/en-us/thunderbird/addon/provider-for-google-calendar/
https://addons.mozilla.org/thunderbird/downloads/latest/4631/addon-4631-latest.xpi?src=dp-btn-primary
File: chrome/gdata-provider/content/gdata-calendar-event-dialog.js
File: module/gdataUtils.jsm