Where can I see all the learned/ignored spelling in Pages 5.5?
Your custom words spelling are stored in this plain-text file:
~/Library/Spelling/LocalDictionary


You can view it from your terminal using:
cat ~/Library/Spelling/LocalDictionary


Or open in a text editor of your choice by using its Open menu item then:

Press Cmd+Shift+G to open the Go to folder dialogue
Paste ~/Library/Spelling/LocalDictionary into the box
Press enter