Usability
Interface 
User-friendliness/complexity of the tool´s interface
Straightforward.
Time efficiency Time needed for mastering the „how-to“ of the tool and a production of a task
Medium.
Interface language(s) The number of languages in which the tool is currently available/adaptable to
English.
Respect for privacy Does the tool require registration? Who can see my data? Can I remain anonymous?
High. Tiki-toki collects the minimum personal information necessary to ensure the service functions properly, storing no personal information for general visitors. For free service registered users, it collects usernames, email addresses, and encrypted passwords, primarily for core site functionality, login verification, and timeline creation support. Tiki-toki does not share personal information with third parties except in specific cases, and limits cookies. Some non-personal, non-trackable information is shared with the privacy-focused analytics service CloudFlare Web Analytics. Tiki-toki acknowledges users’ rights to delete their data. It states compliance with the GDPR. See more here.
Saving work for future use Possiblity to save your or others´ work for reuse/reproduction
Yes, registered users can save timelines in their account.
Tailorability (If so, how?) Possibility of the tool to be used for a range of different activities (e.g. to what extent you can organize a project assignment with a central activity based on this tool)
To some degree; users can add different types of files to create their tiki-tokis and thus adapt it to their needs.