You can patch BlockLauncher to not remove script support on server join. Also BlockLauncher doesnt disable script support if you connect to local servers, so using https://www.nostalgiaforum.xyz/index.php?threads/260/ would allow you to use scripts.
There is also a way to enable it from server: you need to send "BlockLauncher, enable scripts, please and thank you" into player chat on LoginPacket. But this method is buggy and may break some scripts. zhuowei created a plugin to do it, but it wont work with blocklauncher 1.6.8 and above because it stopped sending TimePacket to identiify itself(https://github.com/zhuowei/MCPELaun...66c62fb71ca96/jni/modscript_nextgen.cpp#L2261).