Yes, Sleeknote can be used on websites with multiple languages.
The method for setting up different campaigns for different languages depends on the domain structure of your website.
If your website keeps different languages under one domain, you only need to implement the tracking code once.
When creating a campaign, simply enter your main domain and use the "URL matches" option in Display Settings to specify which pages the campaign should appear on.

If your website uses separate domains for different languages, you will need to implement the tracking code on each domain separately.
When creating a language-specific campaign, enter the domain you want the campaign to appear on in Step 1 of your campaign.
This will ensure that the campaign is only displayed on the appropriate language version of your website.