Your "Kalandra" must be what most histories refer to as Kale
ndra. The transliteration of Turkish/Greek/Bulgarian placenames from the Ottoman/Greek/Cyrillic alphabets into Roman letters on maps of the period is very fluid, depending on the language of whoever was doing the transliterating - the British, French, Italians, Germans and Austrians all used different systems!
Kalendra is now (and was before the Turks arrived) called Kala Dendra, meaning "Good Trees". It's on Google Earth at 41.1, 23.425. The church (no idea if it's the original one!) is on the southwest edge of the present village.
There are some aerial shots at http://www.airphotos.gr/kaladendra.htm
(church on far side in the first two photos).
The name Kala Dendra was contracted to Kalendra sometime in the 1600s under Ottoman rule, but the original name was restored in 1926.
The Wood mentioned (and from which the village got its name) doesn't exist any more, but there was a natural forest of elms south of the village, according to the history here http://www.serrelib....rthra.php?id=19
Wessex Bridge was an army-built bridge over the Struma between Sakavcha and Karadzakoi Bala (now Livadochori and Monoklissia) at approx. GE 41.0292, 23.3888.
On the evening of 15 May 1917, 31st Brigade (inc. 5/RIF) formed the right flank of an attack by 10th (Irish) Division on the Bulgarian lines from Kalendra up to Prosenik (Skotoussa), Kyupri (Gefyroudi) and Bairakli (Valtero). This was in support of an attack by 85th Bde (28th Div) on two outposts known as Ferdie and Essex Trenches NW of Bairakli Juma (Iraklia).
The Official History has a detailed account of the exploits of 85th Brigade, but nothing about 31st Brigade, alas. They were apparently successful though!
The War Diary of 5th Bn Royal Irish Fusiliers should have more details It is at TNA under WO95/4838:
Unfortunately not available online.
Hope this helps