I've noticed that all other bases with either a mix of square and triangle foundation or all square foundation paste at normal height without having to use /paste base height xx

When pasting a base with all triangle foundations the base gets pasted far underneath the map and takes a lot of height changing before finally getting it above ground with /paste base height 29

is this intentional or is this broken?
Love using this for raidable bases and VIP bases

Yes, it is. If the base is built only on triangular foundations, it will spawn at an altitude of 0 (sea level). The author needs to fix it somehow.