Tellraw

extra

Whenever an extra component is used (or the short version of it), the narrator will only say the first part:

/tellraw @p {"text":"Hello ","extra":[{"text":"there."}]}
/tellraw @p [{"text":"Hello "},{"text":"there."}]

Result: narrator only says "Hello ".
Expected result: the narrator says "Hello there." in both situations.

translate with

It work fine with the with component of translate.

/tellraw @p {"translate":"Hello %s","with":[{"text":"there."}]}

Result: Narrator says "Hello there."

selector

The narrator doesn't say selector results.

/tellraw @p {"translate":"Hello %s","with":[{"selector":"@p"}]}

Result: narrator says "Hello ".
Expected result: narrator says "Hello <PLAYER>".

Say

The /say command only makes the narrator say the executor's name

/say Hello there.

Result: narrator says: "<PLAYER>"
Expected Result: narrator says: "<PLAYER> Hello there."

Tell/Msg/Wisper

The /tell command only makes the narrator say the executor's name and the "wispers to you:". Put this in a command block:

/tell @p Hello there.

Result: narrator says: "@ wispers to you:"
Expected Result: narrator says: "@ wispers to you: Hello there."

Side note:

jirauser71590: /say and /tell internally get converted to the JSON text component, meaning

/say Hello there.

will internally be converted to the following:

{"translate":"chat.type.announcement","with":[{"text":"<PLAYER>"},{"text":"Hello there"}]}

and of course

/tell @p Hello there.

will internally be converted to the following:

{"translate":"commands.message.display.incoming","with":[{"text":"@"},{"text":"Hello there."}]}

So their cause is not the same as tellraw's (as tellraw works with with translate with).