How do I add Alt Tags to the homepage slideshow images?

To add Alt Text to your slideshow images, open up Template Editor > Snippets > homepage-slider.liquid.

To set it to the image's title from your theme settings, for example, you could do this:

On line 29, you'll see the below:

                  <img src="{{ img_url | asset_url }}">

Change it to:

                  <img src="{{ img_url | asset_url }}" alt="{{ settings.[img_title] }}">

That will show the alt tag, with the title you enter into Theme Settings for that slide. 

[Later versions of the Bilingual Shopify Theme will have this;  but earlier versions didn't have it as yet.]

Enjoy!