Maybe you can explain why spell checking is somimportant to you?
Professionally, I have been involved in spellchecking, mostly for extreme difficult texts. I think you are asking CL to add the checking of texts, that is only a very small area of the functionality (although they tend to make it far bigger with the fancy title stuff), in that many languages, with the high possibility that there are unlisted words.
As you say, there is the option to check the texts outside the program, like for subtitles (export and import). I would rather ask CL to focus on a flawless video editing experience. Would you not agree?

Quote I would rather ask CL to focus on a flawless video editing experience. Would you not agree?

Several years back I submitted a long list of improvements CL could make to PD to improve it's productivity/usability. These were submitted directly through their reporting facility, with a copy posted here. It included adding spell checking (which pretty much every other text manipulating product has). Then I resubmitted them about every two years. NONE of those productivity improvements have been implemented. I think CL has had plenty of time to implement the productivity/usablity improvements many of us have asked for.