Diverse subpopulations have different needs requiring unique adaptations, even within a single setting (no ‘one size fits all’).

Language barriers.

Differing expectations for mental health services.

Flexibility, openness, mutual respect and cultural humility in teams.

Language and translation skills.

Time and resources for careful thoughtful formative work to inform adaptation.

High clinician and lay health worker workloads.

Insufficient/incompatible health information systems in the two settings.

Insufficient funds and organisational resources, including technology (ie, internet, work phones).

Fragility of community-based organisations and facilities.

Provider attrition.

Many non-specialist providers have high exposure to the same adversities faced by clients.

Flexibility in delivery settings (i.e., from healthcare facilities to community centres and vice versa).

Remote delivery (telehealth, virtual supervision), and ensuring access to requisite technology.

Appropriate training, preparation, compensation and supervision structures to deliver the intervention, including the creation of local supervision infrastructure to facilitate scale up.

Sufficient funds and grant mechanisms for long-term projects in multiple sites.

Robust self-care to support non-specialist providers to mitigate risk from secondary trauma and prevent burn-out.

Different structural factors affecting healthcare access and usage in each setting (ie, different degrees of poverty, community violence and/or stigma).

Different healthcare systems and policy/legal regulations in each setting (ie, laws regulating who can deliver mental health services) led to challenges working with local health authorities.

Changes in political leadership and political will over the life of the project in either setting.

International travel restrictions, especially for visitors from LMICs to the USA.

Ongoing data collection/analysis to tailor interventions to changing contexts.

Legal/regulatory expertise in each setting for issues such as intellectual property or provider regulations.

Allocation of travel funds for team members to visit collaborating sites and learn from one another.

Validation of intervention modalities and tools in new settings takes time and resources.

Need for fidelity monitoring and quality assurance for the implementation of evidence-based interventions.

Sufficient clinical and research expertise to assess adapted versions of interventions and training content.

Digitised provider-support tools can improve intervention fidelity and enhance clinical supervision and care using real-time data analytics.

Iterative feedback and learning.

Sharing procedures, information systems and/or staff across multiple settings.

Sharing complementary expertise (eg, mental health task sharing experience from one setting, community engagement experience from the other setting).

Real-time dissemination of strategies, tools and materials in simultaneous projects.

Providing remote delivery resources across settings can lead to wider than expected capacity building in under-resourced locations.