@Khan saheb you are absolutely correct.
It's common sense. If they are buying decades old platforms and then also an assorted collection, those are for stop-gap use only. Ultimately a Navy like Bangladesh' will standardize with a locally built platform (often in sets of four or so), customized for local use and conditions.
Coast Guard's larger OPV's (Minerva class), Navy's mine-hunters (Ex-RN Island class), Navy's larger patrol frigates (USCG cutters) are all stop-gap measures....that's why they typically don't put brand new weapons on these platforms. These will all be de-commissioned and replaced in about six/seven year time frame with new platforms.