Summary
Creators can use the hash character to create private scores for an objective. Sited from the official creator forms for Bedrock Edition.

This is accurate as the scoreboard command supports this features. The following is a valid command.

scoreboard players set #variable number 99

However when using the execute command to test this entry results in an invalid command. The following is an invalid command.

execute if score #variable number matches 99 run say test completed 

Provides syntax error: Unexpected "#": at " if score >>#<<variable n"

Impact

• Creators cannot use private entries properly when using the execute command.

Expected

• The hash feature supported with the scoreboard command is recognized by the execute command and any other possibly affected commands.

Source

• https://learn.microsoft.com/en-us/minecraft/creator/documents/createaninworldgame?view=minecraft-bedrock-experimental