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Shipping cringe but whatever.
The Japanese Voice Actor for Dawn/Hikari simply made herself available for more cameos (or pestered someone on the staff enough for it) that she was written to show up as much as she did for Journeys including attending the final tourney which in turn makes it appear as either Dawn is undeniably Ash's most loyal friend or she has it down bad for him.
Also Lena and Lyn from XY016 were the animators having fun with what a married Dawn with a child would look like. You could stretch an inference that the orange eye color was chosen because it matches Ash's own but it is indeed, a stretch.
Note also that Lena is the Persian word for Light. So Lena -> Light -> Hikari
pic related is shopped to make Lena look a bit more like Dawn
