Hi Arthur,
Thanks for reaching out.
The issue you’re describing relates to Joomla’s core functionality, not to Helix Ultimate or SP Page Builder. Unfortunately, we don’t provide customization services or support for third-party core features.
We recommend hiring a Joomla developer if you need this behavior adjusted in Joomla 4. They can help you create a custom override or workaround to allow underscores in tag aliases.
We appreciate your understanding, and we’re always here to support you with any issues related to our own products.
Best regards,