I'm not sure if you're arguing over a technicality of phrasing or making a different point that I'm missing.
"IMC Rating privileges entered on UK-issued JAR-FCL and non-JAR-FCL aeroplane licences may be exercised in both EASA and non-EASA aeroplanes until 8th April 2014."
The licence would be a JAR-FCL licence when the IMC rating was entered.
Your Part-FCL licence (with an IMC rating attached or not) will not permit you to fly under IFR in an EASA aeroplane after 8th April 2014. Of course there may be other mechanisms in place by then to preserve the privileges.