I see on the opposite that the custom fields are correctly filled. At least in the input area displayed by WordPress in the Custom Fields metabox. This proves that the custom field prefilling managed by Polylang works well.
I can't answer for the input area displayed on top, since I don't even know which plugin/theme you are using to make this appear. But most probably the author of this plugin/theme did not imagine that some other plugin can prefill the custom fields for a new post and so doesn't display them. So I encourage you to contact him.
EDIT: Sorry, I did not pay attention that you are using Pods.
For Pods 2.3.x, you should use Polylang 1.1.6. Compatibility of Pods with Polylang 1.2+ is forecasted for Pods 3.0. See:
https://github.com/pods-framework/pods/issues/1801