The bug

When you use the name selector parameter you would expect that you select entities by the name you see in the chat or above their head (except if you use translations). However it looks like the parameter does not test nested text components.

Note: This works correctly for the Lock tag of containers, see also MC-123932.

How to reproduce

1. Summon an armor stand with a nested custom name

   /summon armor_stand ~ ~ ~ {CustomName:"{\"text\":\"test\",\"extra\":[\"_test\"]}"}
   

   → The armor stand is named "test_test"

2. Try to select the armor stand by that name

   /say @e[type=armor_stand,name=test_test]
   

   → It fails