Hi,
I see the issue.
There is a need to fix this and I will open an issue in this regard on github.
The reason is that Arpege and ICON provide pressure data (isobars) without any smoothing algorithm as GFS does. The original code in XyGrib dealt with GFS as the primary model so the internal algorithm to show Highs and Lows is set to GFS data and we need to tune this code to "unsmoothed" model data.
Thanks for pointing this out
David