You can report an Optimizely bug by submitting a support ticket through support@optimizely.com

At least that is the way we have used, if its a bug they wil create a bug task, or if it relates to an already registered bug you will get the info.

You’re right, that message looks confusing – it’s coming from the built-in Forms localization rather than anything you’ve configured in your form, so you can’t change it per-form from the UI.

In Forms 5.7.2 this is effectively a text/UX bug in the default language resources. Until Optimizely changes it in a future release, 1 below option you can try:

Override the text via Forms localization:
You can override any of the default Forms strings by copying and editing the embedded language XML and then placing it under your site’s Resources/LanguageFiles folder:

• Extract EPiServer.Forms_EN.xml from
  \modules\_protected\EPiServer.Forms\EPiServer.Forms.zip\EmbeddedLangFiles\ 

• Locate the entry for the description/help text that’s using the wrong field name.

• Adjust the value to the wording you want (for example, remove or correct the misleading field reference).

• Drop the modified XML into \Resources\LanguageFiles so it overrides the embedded resource.

After an app restart, the Forms UI will use your corrected text instead of the default one.

Thanks,