According to https://meta.wikimedia.org/wiki/Interwiki_sorting_order , some communities asked for particular languages to appear at the top of the interlanguage list. They appear in the Interwiki_config-sorting_order message. These are usually languages that are more or less likely to be known to the speakers of the wiki's content language.
Examples:
- Hungarian: https://hu.wikipedia.org/wiki/MediaWiki:Interwiki_config-sorting_order
- Telugu: https://te.wikipedia.org/wiki/%E0%B0%AE%E0%B1%80%E0%B0%A1%E0%B0%BF%E0%B0%AF%E0%B0%BE%E0%B0%B5%E0%B0%BF%E0%B0%95%E0%B1%80:Interwiki_config-sorting_order
- Hebrew: https://he.wikipedia.org/wiki/%D7%9E%D7%93%D7%99%D7%94_%D7%95%D7%99%D7%A7%D7%99:Interwiki_config-sorting_order
- Nynorsk: https://nn.wikipedia.org/wiki/MediaWiki:Interwiki_config-sorting_order
They can be added to the compact list.
Comment: Given Niklas's comment at the bottom, this should be done by reading the sortPrepend configuration and not the MediaWiki:Interwiki_config-sorting_order message. This is more robust.