Good news: from 1.1.0 version, manual setup of line height and char width is not needed anymore, thanks to alexdima (Alexandru Dima).
You can provide other tokenizer algorithms and we can add them into this extension, so Blockman will be able to highlight blocks based on different or more advanced logic, or add support for other indentation based languages.
2) Please don't use non-monospace font. Use only monospace font like 'Oxygen Mono', 'BPG 2017 DejaVu Sans Mono' or other. Block-rendering is based on equal character-frame-widths, because pixel locations of characters is not accessible through VSCode API.
3) If you want to use mix of multiple fonts (like in the image above), Please don't use any non-monospace font. Use monospace fonts which have at least almost same width of character. For example: 'Oxygen Mono' and 'BPG 2017 DejaVu Sans Mono' have not only equal char frame width by themselves alone, but also almost equal char frame width to each other.