οὕτως ἀνόητοί ἐστε, ἐναρξάμενοι πνεύματι νῦν σαρκὶ ἐπιτελεῖσθε; [NA 28]
Are you so foolish? Having begun by the Spirit, are you now being perfected by the flesh? [ESV]
Or, taking ἐπιτελεῖσθε as middle voice, which seems more likely (see BDAG):
‘Are you so foolish? Having begun with the Spirit, are you now ending with the flesh?’ [RSV]
The most noteworthy change that precedes endnote c is the change from ‘be completed’ or ‘finish’ to ‘becoming slaves again’. Is there a difference here between the Greek text and the Aramaic?
Here is the Western UBS Peshitta text from dukrhana.com with transliteration and three English translations by Etheridge (green), Murdock (navy), and Lamsa (purple):
It can be seen immediately that none of the English translations give any indication that the Syriac might support Simmons’ rendering. The word in question is ܡܫܰܠܡܺܝܢ and the lexeme is ܫܠܡ. Jennings gives the meaning as:
The basic meaning is ‘was finished’, ‘complete’. It may look at first sight as if there might be some meanings that could give an idea similar to ‘become slaves to’, as Simmons has it. For example, ‘yielding yourselves up to the flesh’ is not perhaps so far from ‘becoming slaves again to the flesh’. But on closer inspection it will be seen that all meanings of this sort occur under the Ethpa’al conjugation, one of six main verbal forms:
The analysis tool however shows ܡܫܰܠܡܺܝܢ as being in the Pa’el form:
and the meanings given under the Jennings entry above for the verb in this form are all to do with completing, perfecting and finishing:
Given that all Etheridge (‘finishing’), Murdock (‘consummate’) and Lamsa (‘end’) all translate with this kind of meaning, I think it highly unlikely that the analysis tool is wrong here.
I conclude that Simmons’ rendering with ‘becoming slaves again’ is almost certainly not in fact translated from the Aramaic as he claims.