I use two transpilers in my day to day work, cython and coffeescript. In both cases they work really well and save me a bunch of time and effort. However in both cases the transpiler is written in parallel with the source language which always makes it a lot easier and the transpiler obviously supports 100% of the source language.

I have also played with transpilers written for 'foreign' languages and then you do end up in a situation where you can only use a (often badly defined) subset of the source language, and debugging is a pain since the output is often very difficult to read. Still they're handy when you need them and can (sometimes) save you time compared to porting the code by hand.