Sorry, this is in part beside the topic, because it mainly addresses the speech-bubble issues.
Krita’s text tool is currently being redesigned, but whether the rendering you want within the text editor will also be taken into account there, I can’t say, I think the focus is more on the rendering capabilities. But what I’ve seen so far in terms of previews is more than just a milestone and should help the text tool to significantly increase usability.
Speech-Bubbles:
If you were satisfied with the somewhat limited possibilities of the arrows for the speech bubbles of “Rogudator’s Speech Bubble Generator”, then this might be a temporary solution for the time until an interface in your sense is available. There, the speech bubbles are adjusted to the text you type, but you are stuck with the bubbles and arrows provided by the plugin.
The plugin on Krita-Artists:
On GitHub:
A video about it on YouTube:
Michelist