In Sweden, 95% of adult learners at the compulsory school level and 47% at the upper secondary level were foreign-born in 2022. This explains why language learning is in high demand among migrants and why the contribution of Municipal Adult Education in improving employability and fostering inclusivity is paramount. Teachers are expected to design learning activities across synchronous and asynchronous modes to ensure that learners engage. While there is a general call for more research on student engagement in various online learning contexts there are also specific and significant gaps in research in relation to the design, implementation, and evaluation of Learning Sequences and empirical studies of adult education, such as the didactic practices of adult education teachers. This study seeks to contribute by investigating how educational modes influence learner engagement and can inform future learning designs. Over a nine-month period, observations (n=34), were made in both asynchronous (n=25) and synchronous (n=9) modes of second language learning settings, examining teachers' instructional designs. Analysing how designs facilitate learner engagement across learning sequences through Sequential Pattern Mining and Social Network Analysis, the findings show that engagement is significantly influenced by both learning design and mode of delivery. The findings suggest that a combined approach, merging synchronous and asynchronous modes, could significantly enhance learning outcomes. Notably, cognitive engagement—traditionally associated with the self-directed and autonomous nature of asynchronous learning—emerges as a vital component with a broader function. Learning activities characterised by cognitive stimulation frequently precede those fostering other engagement types (behavioural, social, emotional), unveiling cognitive engagement's pivotal role not merely in individual learning but also as a bridging mechanism. This bridging capacity of cognitive engagement underlines its importance in the holistic facilitation of engagement, suggesting that online learning designs must go beyond individual learning to incorporate this mediating role. This insight not only advances our understanding of engagement dynamics in online adult education but also emphasises the critical need for learning designs that leverage cognitive engagement to unify various forms of engagement, thereby optimising the educational experience for adult learners.