Previous versions of MODx are defaulted to english.
It’s not totaly true but a pure coincidence

.
English was the default because with Modx 0.9.6.1
Bulgarian didn’t exist as language for the installer. So
English arrived before (alphabetic order):
French
German
Russian
Spanish
Svenska
With 0.9.6.2, we have added : japanese, norwegian and persian.
The MODx 0.9.6.1 code was:
<select name="language" style="float:left;">
<?php foreach ($langs as $language) echo '<option>' . $language . '</option>' ?>
</select>
And the MODx 0.9.6.2 code is now:
<?php
foreach ($langs as $language) {
$abrv_language = explode('-',$language); // filter of character set extension
echo '<option value="' . $language . '">' . $abrv_language[0] . '</option>'."\n";
}
?>
Where $langs in the two versions is provided by the names of language folders.
So, this is the same thing (alphabetic order). With Modx 0.9.6.2, in addition, as we propagate the language to the admin manager, we are forced to filter the extension (e.g .utf8). I Know it, I have updated this part of code.
So, take care if a guy of
Abkazia ask for a new version of the installer