Emilie does not use the Burning reaction as her primary source of damage, but rather she uses the reaction to help her continuously deal Dendro damage. Thus, Emilie would rather build offensive stats rather than focus on building around the Burning reaction.
Regarding Weapon Choices:
Symphonist of Scents: Keep in mind that while this weapon serves as a decent stat stick for Emilie, using it on her wastes one of the game's stronger buffing weapons since her kit lacks any healing to activate its buff.
Deathmatch: At [R5], this weapon will perform better than , and it will perform a little worse than if she is played in single-target.
Regarding Artifact Choices:
Sets
Deepwood Memories (4): This set has significantly less value on Emilie if someone else in the team can hold it.
Substats
Energy Recharge: Emilie does not need to Burst every rotation in some teams, so Energy Recharge becomes less important.