In the spec,

channel_reserve_satoshis is the minimum amount that the other node is to keep as a direct payment.

And, as my understanding, this means it's the value that the node receiving Open/AcceptChannel should keep.

We do channel.thier_channel_reserve_satoshis = msg.channel_reserve_satoshis
So channel.their_channel_reserve_satoshis is used when checking conditions for our channel reserve and I found it pretty confusing.

Perhaps,
channel.our_channel_reserve_satoshis = msg.channel_reserve_satoshis
and
Channel::get_their_channel_reserve_satoshis is better?