Online form converter doesn't work with multilingual external select

1. What is the issue? Please be detailed.
Creating a simple form that has bilingual labels. Even though I can convert it using recent python script the online converter ( gives me error

Error: ODK Validate Errors:
>> XForm is invalid. See above for the errors.
: Item <label> '${name_key}:label': text is not localizable for default locale [Polish (pl)]!

The following files failed validation:

Result: Invalid

2. What steps can we take to reproduce this issue?
Add a second language label to the xls choices sheet in the fruits example from documentation (

search_and_select.xlsx (10.4 KB)
fruits.csv (104 Bytes)