Transparency in assessments means ensuring their validity, reliability and authenticity. While it remains limited in practice when administering internationally validated literacy assessment tools, one major factor necessitates transparently reporting achievement results in light of learners' linguistic repertoires. Sitting these literacy assessments in bi/multilingual Arab settings, like in the Gulf Cooperation Council (GCC), often eventuates in inequitably assessing learners' Second Language (L2) reading skills as opposed to their First Language (L1). This is because Modern Standard Arabic (MSA) and English, as official mediums of instruction in government and English schools respectively, are in fact acquired second to learners' home language. Drawing on the PRISMA framework, the research yielded 626 peer-reviewed research articles published between 1970 and 2025 across Scopus and the EbscoHost databases, of which 18 were of relevance to the study. The article concludes that extensive research needs to be developed when it comes to transparency in the educational realm. One major factor that needs to be considered is that the diglossic nature of the Arabic language could create a gap in reporting learners' literacy achievement results. The study found that failure to address the diglossic nature of Arabic in reporting learner results is reflected in the varying perspectives on diglossia in research conducted in the Gulf countries. This urge for transparency requires that learners' cultural and linguistic profiles are noted when comparing results with other monolingual test takers. The study also recommends that educators dilute assessment-related challenges and embrace the different authenticities of MSA and Spoken Arabic Vernacular (SAV).