The evolution of the speech and language is gradually accepted as a complex process predetermined by an intricate relationship between biological, socioeconomic, cultural, and family factors. Nevertheless, several eligible studies are still left to be substantiated with the lack of evidences related to culturally diverse and low- to middle-income countries. To fill this gap, this paper will examine the direction of paths between biological risks, socioeconomic status (SES), environmental and cultural factors and child outcomes such as language competence, psychosocial adjustment, and academic performance based on two critical mediatory factors, parental self-efficacy (PSE) and cultural context (CC). It was a hybrid study that used a mixed methodologies approach, i.e., Structural Equation Modeling (SEM) with qualitative validation. A total number of 500 participants were used to obtain qualitative and quantitative data in Pakistan, China and Spain, and a sample of 150 participants was used to collect qualitative data in the form of interviewing of 150 parents, teachers and clinicians. The Smart-PLS 4.0 tested the hypotheses with respect to 5,000 bootstrap samples and processed the analytical insights regarding qualitative themes with NVivo 14. The structural model demonstrated robust explanatory power (R² = 0.534–0.623) and predictive accuracy (Q² = 0.298–0.381). Among predictors, socioeconomic status (β = 0.194–0.231) and cultural and educational context (β = 0.192–0.219) emerged as the strongest positive influences on child development outcomes. Conversely, biological risk factors (β = –0.098 to –0.112) and environmental or behavioral stressors (β = –0.087 to –0.095) negatively affected outcomes. PSE has a decisive role as a mediator since it appears to clarify 2532% of the total effect (VAF). Cultural context significantly moderated these relationships, being most pronounced in Spain (β = 0.21–0.28), moderate in China (β = 0.12–0.19), and comparatively weaker in Pakistan (β = 0.08–0.15). These patterns of quantitative results were supported by the qualitative results, which determine that sociocultural values, parenting norms, and environmental expectations influence a way PSE is translated into the child language and behavioral competencies. This analysis is the initial COMBIMETHOD synthesis of SEM with NVivo analysis of cross-cultural child growth studies that will be very effective towards theory to context translation. Enhancing guided parental self-efficacy with culturally-adjusted interventions is one of the evidence-based avenues that decrease developmental risks and endorse the best language and psychosocial performance in diverse cultural environments.