Trainer cards displayed in red, unreadable

[Aquelite]

I have this problem with several trainer cards that I received from booster packs, and also some cards that my opponents use. I just can't see which card it is and instead see a red card with some strange symbol

 

[DMoCTTA]

I'd say it's A) Your graphic card, maybe your computer is older. I played on an older computer last week and it was zoomed out.
B) your internet speed. I know when I'm on wireless and not direct connect sometimes cards don't load up at all!

 

[Aquelite]

But it's only specific cards, only certain trainers. And they have stayed that way since forever.

 

[Pokealjovin]

Looks like the image for those cards have been corrupted when they were downloaded to your PC. I would try uninstalling the game then re-install it.