Radha Rasa Sudha Nidhi is well known as one of the great Gaudiya compositions glorifying Radharani and praying for Her maidservice. The author, Prabodhananda Sarasvati, is identified as Tunga-vidya Devi, one of the asta sakhis.
Why will Radha's sakhis pray in the mood of the manjaris?
By the matchless grace of Sriman Mahaprabhu, all of his parshadas had access to the reservoir of nectar known as
mañjarI-bhAva-mAdhuri. The following words of Mahaprabhu appear towards the end of the tenth act of Kavi Karnapura's Chaitanya Chandrodaya:
zrI-kRSNa-caitanyaH : evam eva --
vRndAraNyAntarasthaH sarasa-vilasitenAtmanAtmanam uccair
Ananda-syanda-vandIkRta-manasam urIkRtya nitya-pramodaH |
vRndAraNyaika-niSThAn svaruci-sama-tanUn kArayiSyAmi yuSmAn
ity evo’ste’vaziSTaM kim api mama mahat karma tac cAtaniSye ||72||
"O Acharya! I always reside in Vrindavan, perpetually enrapt in the delight of the matchless blissful rasa of my charming pastimes; I will give you a place in Vrindavan, and a body in accordance with your ruchi in which to relish the madhura-rasa of Vraja! This is my one remaining grand task, and that I shall swiftly do."
api ca --
dAsye kecana kecana praNayinaH sakhyaika evobhaye
rAdhA-mAdhava-naiSThikAH katipaye zrI-dvArakAdhIzituH |
sakhyAdAv ubhayatra kecana pare ye vAvatArAntare
mayy Abaddha-hRdo’khilAn vitanavai vRndAvanAsaGginaH ||73||
"Some are in the mood of servitude, some are beloveds, and some are friends. Some are attached to Radha-Madhava, some others to Sri Dvarakadhish, and again, others to my different avatars. I shall bind all of you within my heart, making you attached to Vrindavan!"
Commenting on the first verse in his vyakhya on the 112th tripadi of Prema-bhakti-chandrika, Sri Anantadas Babaji Maharaja writes:
zrIman mahAprabhu rAdhA-kRSNa milita-vigraha zrI-vRndAvane zrI-rAdhA-kRSNa-rUpe tini nitya madhura rasa-vilAse magna ha_ibena evaM navadvIpa-lIlAra pArSada-gaNake_o tA&hAdera cintanIYa rADhA-kiGkarI-rUpe vraja-nikuJje se_i madhura-rasera AsvAdana dAna karibena - ihA_i zrIman mahAprabhura zeSa kAja |
Sriman Mahaprabhu is the joint form of Radha and Krishna. In the form of Sri Radha-Krishna in Vrindavan, he is perpetually steeped in the sweet pastimes of rasa. In Navadvipa-lila, he will bestow the relish of madhura-rasa to his companions in the forms of the maidservants of Radha in the nikunjas of Vraja they contemplate on -- this is the final task of Sriman Mahaprabhu.
I trust this answers the question? Unfortunately, I don't have Baba's commentary on Radha-rasa-sudhanidhi at hand; I am under the impression that he speaks more on this somewhere in there. Could someone please look that up for us?