copyOrMoveChildren: child order reversed when copying to another language

[DenisMir]

Description

When a container content element is copied (or moved) into a different language column in the page module, its child elements end up in exactly reverse order. Copying within the same language works correctly, and the localization wizard ("Translate" / "Copy") is not affected either.

Env

14LTS
Container 4.0.2

Steps to reproduce

1. Create a container (e.g. 1-col-container) in the default language with three children in a known order — A, B, C.
2. In the page module, copy or drag the container into another language column (free mode).
3. Look at the copied container.

Expected: children in order A, B, C.
Actual: children in order C, B, A.

Nested containers are affected at every level; a container whose only child is another container looks fine at the top level while the inner children are reversed.

Cause

Classes/Hooks/Datahandler/CommandMapPostProcessingHook::copyOrMoveChildren() builds the child list reversed per colPos:

$childrenByColPos = $container->getChildrenByColPos($colPos);
$childrenByColPos = array_reverse($childrenByColPos);

That is correct as long as every child is pasted onto the same positive $target, which CommandMapBeforeStartHook::rewriteCommandMapTargetForTopAtContainer() resolves to "top of the container column" — repeatedly inserting a reversed list at the top restores the original order.

However, at the end of the loop the target switches whenever the paste update carries a sys_language_uid that differs from the child's own language:

$target = -$record['uid'];
$newId = $localDataHandler->copyMappingArray['tt_content'][$record['uid']] ?? null;
if ($newId !== null) {
    $target = -$newId;
}

From the second child onwards the semantics change from insert at top to insert after the previous one, while the list is still reversed — so the reversal is no longer compensated. This applies to both the copy and the move branch.