Let's check the latest, updated and researched scholarly translation of R̥g Veda by Brereton & Jamison (2014), because the earlier ones by H.H. Wilson and R.T.H. Griffith are unreadable, full of translation oddities and also have problematic interpretations.
- These women here, non-widows with good husbands—let them, with fresh butter as ointment, approach together. Without tears, without
afflictions, well-jeweled, let the wives first mount the womb.
- “Arise, woman, to the world of the living. You lie beside him whose life is gone. Come here! You have come into existence now as wife of a
husband who has grasped your hand and wishes to have you.”
The sūkta in discussion is X.18, and the verses in discussion are not just X.18.7, but X.18.(7-8), because they have been pretty much discussed, especially in the context of satī, though the verses are emphatically not a depiction of satī exactly. From verse 8, it appears that the widow lies down, temporarily, beside her dead husband, but is summoned back to life and indeed symbolically reborn to become the wife of a new husband (quite possibly her brother-in-law, like levirate marriage as per Sāyaṇa commentary on verse 8). The happy un-widowed women in verse 7 apparently approach the funeral pyre to adorn the widow for her return to life. (Brereton & Jamison, 2014). Together verse 7-8 interpreted in this manner shows widow remarriage and not satī exactly as might be misinterpreted by some.
Hypothesizing the custom of satī in early Vedic period, just from these verses provides an extremely shaky basis, especially when one considers the complete absence of references to the practice in comparison to the subsequent late and post-Vedic literature, which significantly includes rather detailed and explicit descriptions of late Vedic funeral ceremonies. (Brick, 2018)
The translation and interpretation by Brereton & Jamison(2014) referred in the penultimate para, is very much on the basis of ārohantu janayoyonimagre and not ārohantu janayoyonimagne, as you mentioned, which was exposed by Max Müller (Gupta, 2007, p. 57) and many other scholars as well. However, it's hard to say that such an interpolation might be by the British. As it's asserted by Müller, later scholars and according to me, it can probably be from any of the later post-Vedic writers of the text as well. It's possible the Brāhmaṇas who did this replacement may have held the view of satī, in accordance with some of the Purāṇas & Smr̥tis which sanction it, and deliberately did that so as to have the Śruti as well validate that witless, misogynistic practice. Such replacements & interpolations are not uncommon to see in texts.
R̥g Veda has not been actually interpolated by the British, there are manuscripts of R̥g Veda of Śākāla śākhā and of some other śākhās which have been verified and many new editions in Sanskrit have been published by post-independence Indian scholars. What's been done by the British is construing and misinterpreting the verses from a Eurocentric perspective, and that's visible in early colonial writings on the Veda which have been criticized by both Indian philosophers as well as Indologists (for e.g. Staal).
- Brereton, J. P., & Jamison, S. W. (2014). The Rigveda : The Earliest Religious Poetry of India. Oxford University Press.
- Brick, D. (2018). Sati. In M. Kitts (Ed.). Martyrdom, Self-Sacrifice, and Self-Immolation: Religious Perspectives on Suicide. (pp. 162-181). Oxford University Press. https://doi.org/10.1093/oso/9780190656485.003.0009
- Gupta, N. (2000). 4. Socio-Cultural Status: Through the Ages (II-Customs and Problems). In Women Education Through the Ages (pp. 47-78). Concept Publishing Company