The description of the GSE reference frame in English is garbled

[eggrobin]

Spotted in a screenshot by Rad on Discord:

the plane of its orbit around itself

A missing > yields that.

Principia/ksp_plugin_adapter/localization/celestial_strings.cfg

Line 37 in 12ab786

#Principia_ReferenceFrameSelector_Description_BodyCentredParentDirection(Earth,Sun).en-us = The centre of <<A:1>> is fixed.\nThe ecliptic (the plane of its orbit around <<A:3>) is horizontal.\nThe reference frame rotates with the orbit, fixing the direction of <<A:3>>.

[eggrobin]

itself

is from r (reflexive) which occurs multiple times in the phrase between << >>, A:3>) is horizontal.\nThe reference frame rotates with the orbit, fixing the direction of <<A:3.

Interestingly, Lingoona version 1.7 or later detects the syntax error and ignores the <<A:3>:
https://lingoona.com/cgi-bin/grammar#l=en&t=The+centre+of+%3C%3CA%3A1%3E%3E+is+fixed.%5CnThe+ecliptic+(the+plane+of+its+orbit+around+%3C%3CA%3A3%3E)+is+horizontal.%5CnThe+reference+frame+rotates+with+the+orbit%2C+fixing+the+direction+of+%3C%3CA%3A3%3E%3E.&v1=a%5EN&v2=b%5EN&v3=c%5EN&v=1.6.5&oh=1
https://lingoona.com/cgi-bin/grammar#l=en&t=The+centre+of+%3C%3CA%3A1%3E%3E+is+fixed.%5CnThe+ecliptic+(the+plane+of+its+orbit+around+%3C%3CA%3A3%3E)+is+horizontal.%5CnThe+reference+frame+rotates+with+the+orbit%2C+fixing+the+direction+of+%3C%3CA%3A3%3E%3E.&v1=a%5EN&v2=b%5EN&v3=c%5EN&v=1.7.0&oh=1