@mkaras92 I actually took the liberty of sending a message back in November to a moderator who apparently has a close relationship with the developers. In this message I asked him if he could share my post, which I told you about earlier in this discussion, to the developers; where it touches on the same subject as yours with the problems that the Lakota are facing in terms of siege.
It is unfortunate that no action has been made yet to fix this, but the developers have probably been busy with other projects for the game and perhaps chosen to prioritise the requests of the more popular civilisations such as the Ottomans, when taking into account the new units that they have been given from the October update. Hopefully there will be some changes for the Lakota in the next year, where they can train their own siege units from a conventional building.