I'm just gonna go through the steps I take to lead into the problem I am experiencing, i.e. spell check not working. In fact, the spell check doesn't seem to work either with this Adobe Support Community post?
Open Premier Pro 2023
Open media (Movie) and use the voice to text transcription tool
Get the transcript after about 10 minutes and hit the CC option.
I have the check spelling option checked (menu under the 3 dots on the upper right of the captions window)
I begin the media and fix whatever the speech to text may have missed, any dialogue mistakes, breaks, cadence, etc.
At no time during my review of the text/dialogue are misspelled words underlined/identified. (I intentionally misspelled words to test if the check spelling tool was working and it was not)
I hit the Graphics tab since I watched a video and they showed that using the text in the Graphics tab can run the spell check, but it does not even have text in the tab.
I save the SRT file, open it with Notepad, copy the text, create a Word document with the copied text and then run a spell check which is the only method I found to work considering, I'm guessing, a check spelling bug has an issue in Premiere Pro 2023.
I called Adobe and they have not encountered this spelling error yet in PP 2023 and couldn't help me fix the issue.
If I open the SRT file in the Subtitle Edit app, any word that is apparantly misspelled is underlined in red.