This is reference to Sri Narasimha post on Sohamsa list on seeing Ishta Devata in 12th from AK in Vimsamsa. According to BPHS, the Upasana is to be seen from D-20 and following that advice, the logic used Sri Narasimha seems to be correct.
Before going to the discussion on charts, let me state that reckoning houses and Argala for Rahu and Ketu was clearly explained by Krishna Mishra. I dont know whether it is explained in BPHS, if it was how this was missed by scholars ? There are some Jaimini commentaries which take "Tatviparitam Rahu Ketvoh" for the Argala.
In the most of the charts discussed by Sri Narasimha in the post, the Krishna Mishra Navamsa works wonderful. Below, I explain the Jaimini pointers with Krishna Mishra Navamsa. I am writing this post spontaneously and any errors may kindly be forgiven.
1. Ramakrishna Paramahamsa, explained in the article as how Durga becomes Ishta Devata.
2. Sarada Mata - No planet occupies the 12th from AK in Jaimini Navamsa, yet the aspect of Rahu from 9th house of Karakamsa, on 12th lord Mars explains the influence on Durga. Also look at the conjunction of Rahu with Yogada Saturn which contributed to a large extent.
3. Swami Vivekananda - It was a very clear principle from Jaimini thought that how Influence of Jupiter on 12th makes a person "Bramhatma Vadi" and a Vedanti. Look at the two best benefic planet Jupiter and Venus in 12th from AK. Though there is aspect of Rahu on the combination, which doesn't make much difference.
Swami Vivekananda is considered great philosopher and excelled in Vedanta which is a clear attributes of Jupiter influence and if we take D-20 as you suggested, only there is Rahu and Ketu influence which doen't suffice.
4. In case of Swami Trigunatitananda chart, 12th from AK Jupiter, occupied by Mercury and Mars shows the influence of Vaishnava. Look at Mercury is strong being in friends house. There was a clear dictum from Ancient Jaimini works that aspect of Moon sign lord / Moon / or Jupiter leads to traditional Vishnavism. If we take D-20, there is a clear influence of Rahu / Ketu which never attributed to Vaishnavism except the apect of Saturn from Virgo.
5. Srila Prabhupada - I have clearly explained in my article.
Look at the Krishna Mishra Navamsa, Saturn, Ketu and Jupiter occupied the 12th from AK Moon (As you know, we dont consider Rahu to be AK). It clearly shows the connection of Vaishnavism (Saturn).
There is a clear dictum that Saturn in conjunction with Jupiter makes a person a Vaishnavite and follows Ramanuja Sampradaya. Look athe aspect of Venus from Saturn house (Madhva mata Sampradaya) on the 12th lord Mars. Goudiya Vaishnava Sampradaya is believed to be initiated by a Madhvacharya.
The connection of Ketu in 12th inself shows the highest spirtual experience and liberation.
The debilitation of Saturn is lessened by conjunction of Jupiter.
If we take AK as Rahu and D-20 and your logic, we get Jupiter in 12th in debilitation, which is detrimental for spirtuality.
6. Tridandi Chinna Jeeyar Swami, I dont have his chart and hence can't comment.
7. In case of Ramana Maharshi, he is known not for his devotion towards Lord Shiva. He is a Vedanti, which is clearly shown by the Ketu in 12th from AK Moon. The aspect of Moon sign lord Mercury, Venus lessen the aspect of Mars on Ketu. It is a clear dictum the combination of Mars, Venus, Rahu, Saturn with a Jupiter leads a person to a Sanyasi (Virakti). Though the combination doen't occur in this chart in full pledged manner. Yet, look at aspect of Jupiter, Saturn and Rahu on 12th lord Venus making him a Sanyasi. (Is it also called Avadhuta).
Kindly verify whether this much clarity is seen in D-20 as well.
8. Swami Chandrasekhara Saraswati - Look at the aspect of Juputer, Sun and Mars on 12th of AK Saturn. It is enough to understand his devotion towards Lord Shiva.
9. In case of Prof Krishnamurthi, AK is Mars and 12th from him is not occupied by anu planet. A strong influence of Sun, Rahu (from 5th) and Ketu on debilitated Mars led him to Uchhista Ganapati Upasana. This is the only info I have regarding Sri Krishna Murthi and can't comment much on his Ishta Devata.
10. By entering the details given by Sri Narasimha, I get AK as Moon and you write AK Saturn, so no comment.
11. In case of Paramahamsa Yogananda, the AK Venus in Sg with Jupiter and Moon and Mercury in 5th from it shows the wonderful learning in tradition. The connection of Jup, Venus, Moon and Mercury on Karakamsa and its 5th indicate the person a (Prabandha Karta), shows why his autobiography of a Yogi is so revered in the world.
12th is unoccupied, having aspects from Rahu, Saturn and Ketu and Mercury and Moon. Lord Mars is influenced by Venus and Jupiter. So almost all the planets excepting Sun influence the 12th house. As explained in Ramana Maharshi case, the influence of Jupiter, Venus, Saturn, and Rahu leads a person into Renunciation.
The above combinations, I culled from the Jaimini commentaries available with us. Here, as well, I am sticking to the basics. So, my humble request to all is not to ignore the valuable other Jaimini resouces. If we ignore them for the sake of our ignorance of Sanskrit language or the complexity of the Jaimini System, we will be at loss as our earlier generations have been.