Hi! So I've reread your PB and I have a few suggestions.
I don't write PB's, but I know that the pictures need to do half the work. You need to leave a little more unsaid, that the pictures will explain, freeing up some precious words to dedicate elsewhere. Right now your words are leaving nothing for the pictures to say; for example, "Grandma and Grandpa were packing" can be shown in the picture instead.
Most picture books have 32 pages (15 double-page spreads plus 2 single pages). It’s helpful to create an actual dummy. Fold normal sheets of paper in half and put a rubber band around the middle fold line to make a book.
Print out your manuscript and divide the text into 15 parts. Cut and paste them into the book dummy you created, one part per double-page spread. Flip through each page, read your pasted text, and think of an illustration that would go nicely with that particular text, but that brings something new to the story.
If you do this, I think you'll find that you need to switch around your text. I'd start the first sentence with Korra, instead of the grandparents. Children want to know right away who the book is about. I'll give it a try, just to show you what I mean.
On Friday, Korra and Grandma made delicious treats using berries, leaves, and nuts. (pic shows something of the setting of your story. Are they in a house? forest?)
On Saturday, Korra and Grandpa hopped sky-high and ran races. (which Korra always won - shown in picture? is it summer, maybe grandpa is hot?)
Today, Grandpa and Grandma Roo had to leave. “Don’t be so glum,” Grandma said to Korra, “we’ll be back soon.”
“Cheer up,” said Grandpa, and did one giant jump.
“I am cheered up,” said Korra, but he didn’t smile. (picture shows grandparents packing? Korra hopping away?)
The picture ideas you come up with will only be written suggestions when you sub for traditional publishing and won't be up to you but will help improve your story.
Just my thoughts, take what makes sense to you and leave the rest. Hope this helps!