To be able to approve your own plugin translations you have to post in the Polyglots site:
https://make.wordpress.org/polyglots/
a message like this:
“Hello, I’m the author of the {insert plugin name and a link} plugin. Could you allow me to approve translations in my native language (es_ES), please?”
And select “Editor Request” in the “Post Type” dropdown. Hopefully an editor of the Spanish team will grant you Editor privileges for your translation and you will be able to approve it.
Here you can see an example post:
https://make.wordpress.org/polyglots/2018/08/13/pte-request-for-secure-admin-ip/