though Pylint is already doing a pretty well & improving
On the other hand I think the static type checking provided by strongly typed languages is overrated - it will find only the most trivial issues, while any real mistakes in the application logic will still show up at only at runtime.
Also in the Sailfish OS perspective - we have Python 3.4 (letst stable is 3.6), which compared to the ancient GCC version (4.8 I think ?) is substantially newer and should thus enable the use of resonably modern Python features, unlike with the default C/C++ compiler. So I don't really see any real issues with using Python on this and I think it's a really good choice given the current state of the Sailfish OS toolchain.