The short version: research-use designation is a labelling convention, not a legal exemption, and it does not travel across borders.
Some jurisdictions provide a limited personal-importation allowance for medicines, usually bounded by quantity, by a supply period and by a requirement that the substance is for the importer's own use. Others provide none.
The part that matters: onward supply — including at cost, including to friends — is treated separately and much more seriously in most regimes than importation for personal use.
National medicines regulators and customs authorities publish their positions directly, and those are the primary sources for any specific question.
Onward supply is a materially different legal act and should not be assumed to follow the same rule as personal importation.
Prior successful deliveries tell you about enforcement, not about legality.