At work I'm one of the people who maintain & develop the Anaconda installer used by Fedora/RHEL/CentOS and other distributions. Anaconda has a sizeable codebase with a history getting back to 1999. but we don't really see any special Python related issues compared to if it was written in a different language and we can maintain it just fine.

It's certainly true that due to the awesome flexibility and dynamic nature of Python you don't get some of the benefits of static type checking and linting overall is hard to implement (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. So you still need a comprehensive test suite either way & it seems to be less and less acceptable these days to develop nontrivial suftware without having a good test coverage and using CI.

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.