When logging in/out using CentralAuth miniatures of all of the project logos are displayed. Like below

Wiktionary

For Wiktionary the icon is this one.

This is however the logo of the en.wiktionary which differs from that of most other Wiktionaries and, most importantly, from the Wiktionary logo used on wikimedia.org and wiktionary.org.

Suggestion: Change the icon to a miniature of Wiktionary-logo.svg.

Wikidata

For Wikidata the icon is this one. It is the only one of all of the logos to include the project name as text.

Suggestion: Use a square version of Wikidata-logo.svg instead.

Wikinews

For Wikinews the icon is this one. Since it is not square it gets horizontally squashed in CentralAuth though making it almost unrecognisable.

Suggestion: Make it square by adding white-space above and below.

Wikiversity

Same as for Wikinews albeit less extreme.