The np.log function should be replaced by np.log10
See Beau's work at JOV that traces the log function back to the work by Crawford (1936)

With np.log10, the Barten (flat) curve in the example should evaluate instead to:
[0.021876435681538915, 0.014184813713158736, 0.00952448986054018, 0.006680496306613172, 0.004924641286022344, 0.0038228778810919495, 0.003118856932347983, 0.002662754642667843, 0.002367458781369199, 0.0021814667512135366]

With np.log10, the Barten (flat) and Barten (ramp) curves, evaluated at X0=60, L = [0.001, 0.01, 0.1, 1.0, 10.0, 100.0] are:

Barten (flat):
[0.06299067646573944, 0.021876435681538915, 0.008678146175280605, 0.004311183591087381, 0.0027590747863252907, 0.0021814667512135366]

Barten (ramp):
[0.12598135293147888, 0.04375287136307783, 0.01735629235056121, 0.008622367182174762, 0.0055181495726505814, 0.004362933502427073]

which fit closer to Figure 33 of ITU BT.2246 and also Figure 4 of the following paper:

S. Miller, M. Nezamabadi, S. Daly, "Perceptual Signal Coding for More Efficient Usage of Bit Codes," SMPTE Meeting Presentation, 2012