The normal command considers ending in insert mode as an incomplete command and aborts. From help normal:
{commands} should be a complete command. If {commands} does not
finish a command, the last one will be aborted as if<Esc>or<C-C>
was typed. The display isn’t updated while “:normal” is busy. This
implies that an insert command must be completed (to start Insert
mode, see :startinsert)
:startinsert might be the command you are looking for.
:normal A can be achieved by appending a bang (!) to startinsert, as suggested by Ingo Karkat. From help startinsert:
When the ! is included it works like “A”, append to the line.