Custom Events support in lwc:spread throws unknown public property error

[Templarian]

Description

Using lwc:spread={apis} with onclick works since it's a global property, but custom events won't work. Ex: onbar.

Steps to Reproduce

https://stackblitz.com/edit/salesforce-lwc-qhg5sq?file=src%2Fmodules%2Fx%2Fapp%2Fapp.html,src%2Fmodules%2Fx%2Fapp%2Fapp.js

<lwc:component lwc:is={component} lwc:spread={apis}></lwc:component>

Expected Results

The event firing from the dynamic component should trigger the onbar function passed into lwc:spread object.

Actual Results

Error: [LWC warn]: Unknown public property "onbar" of element <x-dynamic>. This is either a typo on the corresponding attribute "onbar", or the attribute does not exist in this browser or DOM implementation.

Browsers Affected

All.

Version

• LWC: 8

Possible Solution

Probably to manually addEventListener each of the on prefixed keys in the object. Don't know if onclick and global ones like it need to be ignored?

Additional context/Screenshots
Add any other context about the problem here. If applicable, add screenshots to help explain.

[nolanlawson]

Related: #4425

[Templarian]

const foo = Symbol('foo');
//... inside of class
apis = {
    [foo]: 'some value only accessible by knowing foo';
};

<lwc:component lwc:is={component} lwc:spread={apis}></lwc:component>

I don't have a use for this, but did notice that symbols are also not binded to the host element with lwc:spread. So it doesn't look to be binding all keys, possibly only keys with a string type.