Marxists tend to forever confuse themselves with endless attempts to save the reputation of Marx/Engels with claims to the ‘real’ interpretation, etc… Up to a point this is an inevitable, essential task, but in the end the left needs to let go of the source figures and move on to a new perspective that is not tied to the past. The cult of Marx/Engels is fatal to a practical movement because the canonization of the founders becomes a cultic, nearly religious mindset.
The question of Eurocentrism is best answered with the approach of WHEE where historical directionality plants a focus on ‘Europe’ in the modern transition. A closer look shows that the issue is not Europe, but the larger operation of a ‘macro effect’ that has a clear rationale for each of its points of transient focus. We can see the contrast of modernity with the Axial Age in the way a parallel manifestation yields to a concentrated focus, which happens to be the transient via ‘Europe’. In the modern case the core globalization ideology is based on technology, and economic development. But the larger effects of the modern transition have rapidly diffused in an operation that is quickly losing its sense of Eurocentrism.
In fact we can see that the dynamic has been a huge success and modern classical music, for example, is a global phenomenon almost with deeper roots than at its source with little reference to any Eurocentrism.
I think Marx/Engels saw the point without the model provided by WHEE: the logic of globalization had a transient Euro-focus (still not fully resolved, to be sure) and this is rapidly dissolving into a global oikoumene, but one now threatened by the formations of global capital, more or less as analyzed by Marx/Engels.