Comment 15 for bug 1522150

The two possibilities here are that ofono is truncating the message after it's received, or the carrier is already sending it truncated to the phone.
The fact that characters like "ą ę" are being replaced by "a e" already indicates that something in the middle (carrier) is trying to replace/remove utf-8 characters from the message.
My opinion is that the carrier is editing the message and the swiftkey emoticon is making their parser break.

If possible, insert the same sim card on another phone with another OS and try sending the very same message. If it arrives truncated, than it's a bug in the carrier side, otherwise if might be something in ofono.

Thanks