Hi Nikita
I've managed to replicate your issue on one of our development systems. It appears that only the last line of the template lines are validated for width. This might be a known technical issue within Smartforms (I haven't looked for an OSS note) All your lines should error as the width of the template is 2cm. If you remove the L3 line, the smartform will then error on L2.
The resolution is either to increase your template width to 7cm or reduce your line widths to 2 cm.