The answer is no.
Right now, all one could do is announce their new filters in a thread. There is also checking github repository.
There are 5 active developers here and their news:
1- @afre - afre's G'MIC diary - #168 by afre
2- @samj - samj Créations
3- @garagecoder - No news source outside of github/gmic-community
4- @Reptorian - Reptorian G'MIC Filters - #613 by Reptorian
5- @David_Tschumperle - Either at twitter or new threads here.