When calculating the cost of a spell, the value for X is chosen before cost-reducing abilities are taken into account.
So, yes, you can do both of those things. Syncopate with X=1 has a cost of 1U, which is reduced to U due to the Electromancer. Likewise, Bonefire of the Damned with X=1 has a cost of 2R, which is reduced to 1R because of Electromancer.
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