The content of size chart is not translabler.

Hello
I am building a system to do business using Printful for Japan. It seems that Printful has recently responded to Japan, so I think it’s a good opportunity to work on it.
Almost completed development, but there are some unsolved problems with translation, can you support me?
When using the size chart, the data is sent to the custom field [pf_advanced_size_chart], but the English text is inevitably updated.
Some information such as the title can be done from wp-admin page of this plugin, but since the content of the size chart seems to be sent by API from the printful site, I thought that it could be set from the printful console.
But I can’t find the available setting option.
Can you tell me how to fix it?

King Regards
KAZUKI