Designing dimmer circuit for main
There is creepage protection for 2.5kV impulse from  IEC-664 cat II which requires an air slot gap in case of dust accumulation shown by routed grey zones.

The resistors must be rated for this as well and may need 4 parts for this.

Triacs use REFDES Q1 not D1 and trace width must support any surge current of expected loads.

It is bad practice to have Screen printing between high voltage exposed pads.