Changing font size in text element of cell [CONNECT MDL C++]

Hello guys! I have a question.

I want to do following: 

1. Retrieve element descriptor of a given cell and duplicate it.
2. This cell contains text elements, I want to modify their font size. 
3. During whole process, display said element descriptor in temporary mode.

Before I was working with V8I implementation, here everything worked fine :

I iterate through said cell descriptor. Whenever I found element with type TEXT_ELM, I changed its font size.

For extraction I used:

mdlText_extract(to extract TextSize from element).
Change parameters in extracted TextSize structure.
Recreate element with new font size, using mdlText_createW(myElement,myElement,NULL,NULL,NULL,&extractedSize,NULL,NULL,modelRef)

And all worked fine. However, in CONNECT it doesn´t work as expected. I managed it to work, so it changes the font size, but styling and transform suddenly disappears, so I´ve decided to check the new way with EditElementHandle and TextBlock API.

What I tried to do was (simple test to replace existing text) : 

    ElementHandle eh(out,modelRefP); //out is my MSElement extracted from MSElementDescr iteration i talked before
    EditElementHandle eeh(out, modelRefP);


    // Check if the selection is a Text element.
    ITextQueryCP textQuery = eh.GetITextQuery();
    if (!textQuery || !textQuery->IsTextElement(eh))
        return 1;

    // Extract the TextBlock from the Text element.
    ITextPartIdPtr textPart;
    TextBlockPtr textBlock = textQuery->GetTextPart(eh, *textPart);
    if (textBlock.IsNull() || textBlock->IsEmpty())
        return 1;


    // Get the string from the Text block.
    WString str = textBlock->ToString();
    if (str.empty())
        return 1;

    RunPropertiesPtr runPropP = textBlock->GetRunPropertiesForAdd().Clone();
    
    DPoint2d fontSize = runPropP->GetFontSize();
    fontSize.x = 20;
    fontSize.y = 20;
    runPropP->SetFontSize(fontSize);
    textBlock->SetRunPropertiesForAdd(*runPropP);

    CaretPtr searchStart = textBlock->CreateStartCaret();
    CaretPtr end = textBlock->CreateEndCaret();
    textBlock->Remove(*searchStart,*end);

    EditElementHandle eeh2;
    textBlock->AppendText(L"Test");
    TextBlockToElementResult res2 = TextHandlerBase::CreateElement(eeh2, nullptr, *textBlock);

My idea was to remove and re-enter same text with different properties, because I couldn´t find a way to do it without that (maybe there is some? Remapping doesn´t involve font size) and changing the RunProperties affects only actions that happen after it is set...

And, as you maybe expected, nothing happens, the text is same. I know that you can call AddToModel (then it appears in model, but the original is still same). I also saw ReplaceInModel function, but the elements have no ElementRef yet.

I´ve tried this (with a little hope):

*out = *eeh2.getElementP();

But i got segfault during the iteration of next elements

Do you guys know how to approach something like this?