hello
First, in the future when you have questions in english, there is a forum for that here: http://www.mauricefernandez.com/forum_eng/ .
This forum is for hebrew speakers.
To answer your question, what I have learned over the years is that when it comes to astrology (and life in general), i don't necessarily go by "what makes senses" to our logic, but rather by "what works!"
Western Astrology and the Tropicl zodicac has proven to be 100% reliable and that is what is important for me.
We don;t really know how and why astrology (sidereal or tropical) really works... but we know it does. So, I go with the facts and I leave my logic on hold until further discoveries will better explain these mechanisms.
The fact that we don't know why something works, doesn't mean it doesn't!
Astrology is not completely related to objective phenomena, for example:
Mercury doesn't really retrograde in the sky - it is only apparently so from our point of view - Yet, it surely influces differently at times of retrogradation.
The earth is not really the center of the solar system, and yet, astrologer perceive it as such - and it works as far as astrology is concerned.
So, these two examples are just the beginning of our realization that objective phenomena is not necessarily what matters with astrology. What matters is our subjective perception of the phenomena.
The Tropical/Western zodiac is based on our seasons with 0 aries Sun representing Spring. This is our subjective experience... and it works!
The Sidereal Zodiac represnets the objective picture, and I beleive it to also be valid - however, it probably works better for certain types of measurments and not others. There are many dimensions to our lives; both system may be valid indeed!