Was Germany moving from an empire towards a constitutional monarchy at the end of WWI?

Though I would disagree with Pseudohistorians claim that the German Empire was always a constitutional monarchy (unless he/she really just means that since 1871 there was a consitution and a monarchy), from what you mentioned in the other comment here you are curious if the German Empire was on the path to a British styled constitutional monarchy after the October amendments passed on the 28th?

If this is correct, my honest opinion is that it is truley a moot question. The amendments passed on the 28th of October and the Kaiser abdicated on the 9th of November, so these massive changes were in effect for 13 days before they became completely null and void.

What was clear for some time was that the Kaiser was going to lose power and social democracy would finally have its day. I believe a constitutional monarchy like the British would have been an acceptable state of affairs to the MSPD and Friedrich Ebert, but this is again a moot point considering the actual state of affairs in Germany at the time.

The Kaiser also hated social-democracy and liberalism, so anything he did in terms of compromise, was a desperate act to try and keep up the war effort. So I wouldn't see anything he did as some sort of progression towards a more liberal system on his account. If (magic 'if') Kaiser Wilhelm had only abdicated as Kaiser, for example, but kept on as King of Prussia, and if (magic 'if') he had the kind of support he did before the war, I doubt he would have given into the authority of the social-democrats, regardless of the October Constitution.

I hope this is somewhat of an answer!