when it comes to this and (when it comes) to that

Und streich "the" von "scratch":
start from scratch

Ich würde auch am Anfang sagen:
"However, in terms of platform and application development Java FX lags behind."

Was hingegen die Entwicklung der Plattform und von Anwendungen angeht, hinkt Java FX hinterher. Denn mit Java lassen sich zwar sehr gut traditionelle Anwendungen realisieren, doch bei der Darstellung von Webinhalten außerhalb des Browsers und für Multimedia muss Sun annähernd bei Null anfangen.
Kommentar
What is hindering the development of the platform and applications is also making Java FX lag behind.This is because traditional applications can doubtless be properly implemented with Java, but when it comes to displaying Web contents outside the browser and dealing with multimedia applications, Sun is having to start practically from scratch.

A few small points. Tenses etc. What do you think of the multimedia bit?

i think thats right..the multimeida thing..
thank you very much.