Regarding Nilsaraswati mantra and Tarai w'd like to add my experience and
exposure to all seekers -

Tara is one mahavidya of 10 mahavidyas of shakt tantra system all 10 approaches
to same mother divine the nature itself, in the past while i was doing
experiments to understand it, i chanted mantras of each and every mahavidyas but
mainly i chanted maa durga's one mantra which is given by my guru.

There is a Siddha TaraPeeth in Bihar, Almost at same peiod of Bhagwaan
Ramkrishna Paramhansa, in the Tarapeeth there was equivalent enlightened tantra
siddha, called VamaKhepa, he is suposed to be alive in his astral body even
today, my guru in 80's decades went there to chant mantra sitting on His
Panchmundi Asan, he was doing his mantra jaap but in the midnight all of sudden
his body seemed to be caught up by sth, he was not able to play even his
fingers, that time one sage appeared and asked him "where is ur uttarsadhak (who
looks after u), as he went alone, there was none, as my guru was not able to
speak, he just replied in his mind but this was understood by the next person
and then he touched him, it was like a thunderbolt, but mu guru was freed up and
continued his japa, the next person in the morning asked him why he choosen to
sit on maha siddha's asan there ? he replied it was his desire to experience the
presence of great BamaKhepa, the next person smiled and told him
to not to dare it alone in future. then he ordered him to leave the place as it
was a shamashaan, my guru left the place but there was no vehicle available,
then that person said u may get one Tangaa (cart) after few minutes one
tangawala came to that place and my guru sat on the tangaa, while reaching at
nearby railway station, the person who was running tangaa asked for his payment,
my guru gace him his blanket , while giving he happened to see his face and
surprised he was the same saint who helped him in the night.

I also once wished to meet any great son of mother divine, and that time only i
was chanting tara mantra, i just completed my master's in computer science that
time and once in the morning, while i was going to institution where i was
teaching , i took a bus, it was half filled, in all the seats for two, one was
occupied by girls but in one seat there was a saint, not looking good, too old,
but i thought i can enjoy his company, i sat beside him in the same seat, i saw
he had some scriptures and on one of the scriptures it was written sth abt
"Tara" i was curious to know abt "Tara and Vama Khepa", i asked him what goddess
he worshipp ? he replied "like Kali" further i asked him "what's his Cult" he
replied "Tara Tantra", i asked-"Do u know Vama Khepa", he smiled "Are Kitne
Khepa Khap Gaye, what Khepa u want?", means "countless Khepas are lost in bhakti
of tara, what khepa u want ?", i asked - "same that i rememer this time point of
time", he again smiled and said - "see, forget
khepa and do ur sadhna seriously, when world sleeps sadhak does sadhna and when
sadhak wakes up all sleeps", next i asked "have u ever met god and see it, he
answered - have seen so much in my life, what abt u, when u will see?" as i was
not confident that ever i can meet the almighty it just striked to me that i can
also see and meet my mother god. i was sunk in thoughts and he asked me what i m
wishing, offered me to have one wish and he promised me that will come true,
being a jobless youth, i just wished for a better paying job and next month i
got even without applying for. but after i wished in my mind, he told me "he
came to Bhopal for a purpose and his purpose is completed" and directed me to
get down as my place has come, i noticed exactly it was my bus stop, but i
decided to go further with him, but he denied and in the next bus stop he told
me to get down as he moves alone where ever he wants to go".

after i got down, i wondered if he was Vama Khepa itself ?

I have no idea but u can deduce same Tara is worshiped by hindus and adopted by
budhist also. who can deny the power and presence of mother god in the world
which is created by her only.

I also came to know and chanted Neel Saraswati Mantra and worshiped mother, i
have heared that Aadi shankara also worshiped Neel Saraswati Mantra in the
kasmir. may be it's also adopted by Budhist upasakas.

dont go by pronounce just apply ur inner feelings and u will reach to correct
pronounciation somhow mother will guide u as i was guided. never feel it's
harmfull to u. mother cares us always.

regards,
Lalit Mishra.