If you don't set a label property on the nested field, info.magnolia.ui.form.field.definition.FieldDefinitionKeyGenerator#keysFor fails with NPE since the name of the field is not set. To reproduce:

1. /tours/dialogs/components/tourTypeTeaserRow.yaml Remove the label property of the field
2. Open tourTypeTeaserRow dialog on the home page.

   Caused by: java.lang.NullPointerException
   	at info.magnolia.ui.form.field.definition.FieldDefinitionKeyGenerator.keysFor(FieldDefinitionKeyGenerator.java:64)
   	at info.magnolia.ui.form.field.definition.FieldDefinitionKeyGenerator.keysFor(FieldDefinitionKeyGenerator.java:55)
   

1. info.magnolia.ui.form.field.definition.MultiValueFieldDefinition#getButtonSelectAddLabel/getButtonSelectRemoveLabel should be annotated with @I18nText so we can use auto generated keys.
2. Then the translation in info.magnolia.ui.form.field.factory.MultiValueFieldFactory#createFieldComponent should go away.