Trying to add Season/Episode into description

For personal reasons, I'm trying to add the Season/Episode number at the start of the description, if they exist.

I'm doing this by creating a temporary element, temp_2, but this sets my new element's string to S1 E1(system="onscreen"). .

So I'm then trying to clear up the element by using some .modify.

Code sample:

temp_2.modify {set('index_episode' not "")|'index_episode'}
temp_2.modify {replace|(system=onscreen)|}
description.modify {set('index_episode' not "")|'(''temp_2'')' 'description')

This, even though pretty hacky, works, but it produces results like:

(S1 E8. ) Serialul prezintă lumea plină de opulență, dar extrem de periculoasă a comerțului cu diamante

I've tried to replace|. | and everything I could think of - but it simply does not work, I'm at a loss on how to actually remove ". ".

Can anyone shed some light on how to do this? Or, maybe there's a better way to achieve the same result?