[Resolved] How i can translate serialized value of dynamic conetn?

Hi there!
I have dynamically added stuff for property. Check screenshot.

This is meta_value of meta_key with name 'fave_multi_units'

a:3:{i:0;a:6:{s:13:"fave_mu_title";s:7:"HOUSE 1";s:13:"fave_mu_price";s:5:"95000";s:12:"fave_mu_beds";s:1:"4";s:13:"fave_mu_baths";s:1:"3";s:12:"fave_mu_size";s:3:"140";s:20:"fave_mu_size_postfix";s:2:"m2";}i:1;a:4:{s:13:"fave_mu_title";s:7:"HOUSE 2";s:13:"fave_mu_price";s:6:"750000";s:12:"fave_mu_beds";s:1:"4";s:13:"fave_mu_baths";s:1:"3";}i:2;a:4:{s:13:"fave_mu_title";s:7:"HOUSE 3";s:13:"fave_mu_price";s:7:"850000 ";s:12:"fave_mu_beds";s:1:"4";s:13:"fave_mu_baths";s:1:"3";}}

This can contain more then one, let say some of them can be 3 another 7 other 12 etc.

Which is the best way to translate those kind of data?

I already read stuff here: https://wpml.org/documentation/support/language-configuration-files/#custom-fields

So i believe its shold be like this:

<custom-fields>
<custom-field action="translate">fave_multi_units</custom-field>
</custom-fields>

<custom-fields-texts>
<key name="fave_multi_units">
<key name="fave_mu_title" />
</key>
</custom-fields-texts>

* Is this correct? How i can check if this is correct?
* Also i wold like to know where i need to put the wpml-config.xml file if i use child theme?

Also I am worried about performance of this kind translations. More data more query etc...

May be there is a way to translate only "fave_mu_title" and save space database tables because probably we will have a lot of metadata like this...

Thank you!