baustein | Baustein is a component library that we use at Lyst | Frontend Framework library

This line in your Callback1 function:

i don't know if this is the mistake , but i think thay in your AJAX response whe you set the value in the input the "id" is wrong .

When you create a input in a form in yii2 his id by defaut is "nameModel-attribute" , then in you case it is "textbaustein-bodytext", and in you JS you must write like that .

Inside of read you reallocate buffer for structures storing a new value in lego and invalidating previous once, however lego is a function parameter so calling code still has an old (now invalid) pointer legobausteine. If you are going to reallocate it then you need to pass a pointer to this pointer. Also when you initially allocate buffer with one item for legobausteine in main it is never initialized and initially contains garbage.

See https://www.w3.org/TR/xslt#import, "The xsl:import element children must precede all other element children of an xsl:stylesheet element" so try moving the xsl:import up before any other child element. Also Xalan is an XSLT 1.0 processor so setting version="2.0" in your code sets it to forwards compatible processing mode which is usually not a good idea to get precise and good error messages.