Some seemingly irreconcilable facts (aka "We were East Syriac, but ...")

Apart from overly partisan historians whose faculties of reason have been clouded by either:

1. distorted teachings
2. the desire for a "politically correct" background

it is generally recognized that, before the arrival of:

1. the Latin Rite Roman Catholics in the 15th century
2. the West Syriac Rite Oriental Orthodox in the 17th century

the Nasranis were of the East Syriac Rite. It also seems that the 15th century schism in the East Syriac Church of West Asia that resulted in the creation of the Chaldean Catholic Church in Mesopotamia (who split from the Church of the East, using the East Syriac Rite but in communion with Rome), affected the Nasranis of Kerala. That is, prelates of both the Uniate Chaldean Church and the older Church of the East visited and helped administer the spiritual affairs of the Nasranis prior to the arrival of the Portuguese.

However, there are some strange facts (to me at least) that disturb the story.

1. The Church of the East seem to have been opposed to the use of images and icons in Churches. However, many supposedly old Churches in Kerala have murals painted inside the Church. For example, the following all have murals painted in the Church, and sometimes even behind the altar (facing the people):

1. the Orthodox Church at Cheppad.
2. the Orthodox Church of St. George at Palliakara.
3. the Churches at Angamali

Something seems wrong. Either:

1. the Churches are not as old as have been reported, and were constructed either:
1. during our Chaldean phase (but were the Chaldeans any more forgiving of images in the Church?)
2. during our Roman Catholic phase (i.e., under Portuguese domination)
3. during our Syriac Orthodox phase
2. the East Syriac authorities didn't seem to care with this local aberration
3. some Churches were, perhaps, not originally under the East Syriacs. Were there other Rites co-existing alongside the East Syriacs in ancient times?

To be honest, I don't think option 3 is all that plausible, since we have no literary evidence to support it. But at the same time, most of our oldest evidence seems to be from the 15/16th centuries --- given the climate of Kerala and the human penchant for revisionism, is it possible that earlier evidence might have just been destroyed?

Any other ideas?

2. The Tharisapalli of Kollam. Some report the original name of this Church as "Threesai Shubho." This term is used by the Syriac Orthodox Church in its official Syriac name (ref: wikipedia)---it supposedly means "Orthodox."

What is the origin of Tharisapalli? Are there any indications that it was not of the East Syriac rite? Or, since every Christian sect claims to be "orthodox" and "catholic" (i.e., the one true, canonical, universal apostolic Church) is this a non-issue: that is, did the East Syriacs also use a term similar to "Threesai Shubho" to refer to their faith?

3. Why doesn't the East Syriac Rite exist anywhere other than Ernakulum, Kottayam, Alleppey, and Thrissur? Did everyone in the southern districts decide, unanimously, to move over to the West Syriac rite? Were there no "Pazhayakoor" (i.e., loyalists of the old East Syriac rite) in the South?

Perhaps, since the process was gradual, people in the south didn't really notice that the rite changed---after all, the Puthenkoor didn't switches Rites over night as soon as Mar Gregorios Abdul Jaleel came in the 17th century, but rather over a span of two centuries.

Or perhaps the Pazhayakoor in the south just merged with the Latin Rite Catholic Churches of the south---again, in a gradual manner?

At any rate, it is strange that the Pazhayakoor/Puthenkoor split only appears to have occurred in the Ernakulum-Thrissur-Kottayam-Alleppey areas.