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As a first attempt, I labeled a data set with both Espaloma and Sage 2.1.0 and compared the values they assigned. Two of the torsions, shown below, had deviations between the Sage force constant and the average Espaloma value of more than 10 kcal/mol. These correspond to torsion IDs t129 and t140, respectively.
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For these torsions, I replaced the Sage value with the average value from Esplaoma in the force field, and ran benchmarks on the OpenFF Industry Benchmark Season 1 v1.0 data set, yielding the plots below. I didn't expect to see much difference from such a small change of only two parameters, but it's encouraging that it didn't ruin anything, at least. The eps-tors-10 results might even be very slightly better, as desired.
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As shown in the figure below, all of these outliers are due to C-C bonds where one or both C is attached to an O, usually a carbonyl or carboxyl group.
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b7
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b16
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b4
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b21
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b6
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b10
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b9
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b13
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b59
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b3
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b19
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