first of all thanks for Qoomail, it was needed. People on symbian really miss app like 'taptalk' , maybe you should consider development in that.
Tapatalk use its own mechanism to get data from a forum.
At first is the question, if a third party like us, can use this mechanism and if there is an API to develop it. If not, it will be hard - very very hard.
Another idea is to interpret the html-site of a forum, but these sites are maybe very heavy and big and this will cost a lot of mobile data load and a lot of computing time - means heavy battery drain.
Very though, so this will not a project for us - next time
Nevertheless its interesting, why nobody develop such an app for symbian...