Naming Images files and Alt Text when shared in diferent language sections of a manual multilingual site

Hello,

My question is concerned to manual multilingual sites (bilingual), which present a folder structure to deal with different language sections. For instance, like english and portuguese:

/en/home               /pt/inicio

I'm new at Squarespace and still at the idealizing phase, and I was wondering how to name the image file names, if they will be shared by different language sections. I mean, if I create the whole english website version first, then duplicate all pages to create the portuguese version, of course replacing translated texts, correcting links and organazing the pages in the right folder... how to deal with the images in relation to seo, since they are shared by the same diferent language sections? In this case, the image file is composed by english words but is also used in a portuguese page.

An example: if there's a photo of a yellow car in an english page named "yellow-car" and its Alt-Text as "a yellow car parked on the street", how to deal with this very same photo used in the portuguese version page? Only changing the Alt-Text of it, it´s going to help with the seo or it still will be negativelly affected? There's also the option to duplicate the photo, and use each one named in its proper language and then use it in their proper language section, but Google would interpret this as duplicate content, right?

If I change the name of the image file (inside one of the language versions using the Squarespace interface), this change will affect only the image file on that language version, or in both sections?

Besides, in this type of manual multilingual site we usually find a cover page  with two buttons, each one directing to the first main page of each language section. Which one of these pages is read by Google as the most important (SEO)? The cover page, or each one of the main language pages? Is it also necessary name of the cover page as "index"?

If you could give some help about all this, I would be greateful.

Nobody can give some help about this topic?