query.get_equipped_item_name only returns new names now, breaking old stuff

Partner Rank: 2

Verification builds: 1.16.100.58, 1.16.100.59
Regression builds: 1.16.40

Summary: As of the item flattening, query.get_equipped_item_name returns only the new correct item names even in old worlds. This breaks old maps.

Impact: This breaks the following published Everbloom maps in minor ways:

• Nether Monster Hunter (fireball → fire_charge & totem → totem_of_undying)
• Modern Furniture (spawn_egg → various)
• Trolls & Treasure (netherstar → nether_star)
• Knight School (totem → totem_of_undying)

Other teams may have more severely broken content.

In addition, due to the rename of map to filled_map, vanilla is broken: MCPE-100259.
This also affects all maps in which we had to override the player, copy/pasting the vanilla definition:

• Mermaid Life
• Ninja Parkour
• The Shrinking Potion
• Wildlife Explorers - Ocean

Repro Steps:

1. Download and open Modern Furniture
2. Take a furniture item from the creative menu
3. Enter adventure mode
4. Hold the item in your hand

Expected Results: You silently switch to survival mode

Observed Results: You stay in adventure mode

Screenshots/Videos attached: Yes

Notes: For some reason, the spawn eggs can be used in adventure mode now, which was not the case before. This is MCM-1194. Ultimately, these two bugs cancel each other out, making the map playable! But this is still a problem. The other two maps have no such happy coincidence.
Also note that returning only the wrong old names will break pending maps So good luck with this one