I sent a DM to the Kobo Help team on twitter about this and is supposedly with the development team but decided to post here just in case someone sees this. Worth a try.
I use my device in Japanese and when using my kobo with PDF files, when using a dictionary in words, I cant select the whole word. Long pressing a word, only shows me the definition of one character and not the entire word.
This works with epubs books normally because I can select the word appropriately, however with pdf it doesn't give me an option to select the size of the word. Following is a quick video demonstrating
this.
With epubs, regardless of the orientation, I can select the size of the word appropriately. As seen
here
Would love to see this fixed since even though I used a PDF file with pictures and selectable text, it doesn't work with a pdf file with pure text.
Thanks in advance and sorry for my poor english.