Given this:

To Reproduce I need define Geneva configs as below, but get type unavailable. Looks like bicep has no support to Geneva configs

and

If not, is there a known workaround to add these settings in a bicep template without the resource?
Originally posted by @shcherbin in Azure/bicep-types-az#1843 (comment)

as well as a direct e-mail inquiry about work-arounds...

I think the warning should probably be more clear about the actual effects. Something like "Resource type "Microsoft.Web/serverfarms/firstPartyApps/settings@2019-08-01" does not have types available. Either the type or version does not exist, or Bicep does not yet know about it. This does not prevent attempting deployment, but does mean Bicep may not be able to provide Intellisense or detect potential errors."