confirming config.php variables

[K Lerner]

I'm trying to resolve the upload issue I mentioned in 

https://groups.google.com/g/resourcespace/c/mwWBQPOEM-I .

Copilot suggested adding these to config.php:

$uppy_max_concurrent_uploads = 1;
$ajax_message_polling = false;

$use_legacy_uploader = true;

I don't see any of these in config.default.php, so I assume Copilot invented them and they won't actually do anything?

Is searching config.default.php the best way to confirm whether a variable actually exists in Resourcespace?

Is there any harm in putting a made-up non-existent variable into config.php?

Thanks!