I agree that the term, Queen Alexandra's regal circlet, is perhaps best, even though I am now wondering if this jewel is still a complete circlet.
I have discovered that there has been long standing confusion - at least in press reports - regarding the naming of the crosses in the various jewels.
For example - On 7 February 1911, The Times reported Queen Mary wearing a "glittering crown" at the Opening of Parliament. It was described as "The crown which had not before been worn by the Queen appeared to embody a design of fleurs de lys, with the Royal Maltese Cross in diamonds" Whether HM was wearing Queen Victoria's Regal Circlet or her own crown is open to conjecture, but the description of the crosses is inaccurate.
Again, in The Times 22 November 1933 Queen Mary at the Opening of Parliament was described as wearing a "diadem of diamonds ... in a design of alternative fleurs de lis and Maltese crosses."
In The Times, 25 September 1861, William Polo, in describing the Imperial State Crown of Queen Victoria, described the crosses as Maltese crosses, which they are not.
Perhaps most surprisingly of all (as there is no possibility that HM wore anything other than her own crown) The Times on 20 July 1938 described QEQM as wearing "... an open diamond tiara of Maltese crosses and fleurs de lys, with the Koh-i-noor diamond in the centre." This was for a dinner at the Elysee Palace on the State Visit when QEQM wore her own crown. Queen Victoria's Regal circlet had been broken up so the diamonds could be used in QEQM's crown and Queen Alexandra's Regal Circlet was in Queen Maud's possession.