Right now I'm subtitling a documentary that has interviews in Arabic, Kurdish, Turkish, French and German. What I've concluded is captioning in Premiere is not great. You would think subtitles are straightforward given all the years we've had to develop something that works, but working on a documentary that has six languages, I've found it to be a rather complicated technical process. Two good solutions I've found are 1) Exporting PNG files with InDesign or 2) Exporting a FinalCut XML file from an SRT (subtitling) file using a German-made software called Annotation Edit. Both have their pros and cons.
For InDesign, watch this video: https://vimeo.com/80445034
Pros: Free if you have InDesign, Text can be globally formatted.
Cons: You can't edit the actual text once it sits in Premiere, you have to know the time codes of the translated subtitles and place them in yourself
Best for: Lower thirds. If you need change style or color to your text, you can update the PNG files and lower thirds are changed all at once.
Annotation Edit, on the other hand, creates Premiere's text files, and it uses time codes.
Pros: Text is editable in Premiere, and the text is imported with a time code.
Cons: Expensive (245 Euros), the software can be glitchy, and you can't make global changes. It exports a Final Cut XML (which Premiere can read) and provides time code for where text starts and ends on a sequence. Now, if you want to update those text files and you've already cut them into an assembly, there's no way to really do that without either clicking into each text file and updating the text or restarting the process again with your newly assembled text.
Best for: Long segments of interviews or translations. You also need to work with a translator to create an SRT file that has start and end time codes around each bit of text that will render into subtitles. We've made our SRTs through the sister software, Annotation Transcriber. This is what we've relied on for the documentary. Another one is Aegisub.
One new software I've found that does some pretty cool transcribing and subtitling is Trint. Right now it's in beta version. It analyses an mp3 or video to transcribe English with decent accuracy. The interactive transcript lets me quickly find and correct any of the words in the transcript. Also Trint gives you the ability to export the transcript into an SRT file. If you pair Trint with Annotation Edit, you can get full English subtitles in Premiere pretty quickly and painlessly. It costs about $15 / hour of recording.
For each of these, it cuts down on a lot of future work if you have someone dedicated to working through each transcript and file and ensuring things are accurate and structured evenly before they go into Premiere.