At first thanks for the replies.
I like the idea of integrating MTC as an MediaWiki extension. The
project is based on standard C++ and thus is corss-platform, which
makes it technically adaptable to MediaWiki. As well, I won't mind to
release it under GPL once it is finished, which should suffice the
legal part.
However, there is still much to be done about the syntax. All I can
say at this point is that I am looking forward to cover all current
functionality of templates, and improve it where it is possible. If
you have further ideas I will gladly consider them.
Thanks in advance