In the example above, the charts series label (and therefore also the chart legend) is translated using page item P1063_LANG_AVERAGE_SAL.
Note that in the chart series SQL, make sure to add a space after the column alias like this: "&P1063_LANG_AVERAGE_SAL. ". Otherwise you'll get an parsing error because Oracle thinks the label is null.

The x-axis is formatted in the chart series query using page item P1063_NLS_DATE_LANGUAGE.
The y-axis and chart labels are formatted in the chart xml using page items P1063_NLS_NUMERIC_CHARACTER_G and P1063_NLS_NUMERIC_CHARACTER_D. Note the use of the backslash in the set_page_items process, needed to escape the comma character. You need to use Custom XML for the chart, and change the <format> tag as shown in the code below.

You'll probably want to use FSP_LANGUAGE_PREFERENCE and apex_lang.lang for these translations in real applications, I just used a select list and some page items as a quick example.

Page

Identification
	Page ID	1063
	Name	Apex - Charts - Translate Charts

Item

Identification
	Sequence	10
	Name	P1063_FSP_LANGUAGE_PREFERENCE
	Display As	Select List
User Interface
	Region	Chart
List Of Values
	Display Extra Values	No
	Display Null Value	No
	List of values definition	STATIC2:English;en,Dutch;nl

Item

Identification
	Sequence	20
	Name	P1063_NLS_DATE_LANGUAGE
	Display As	Hidden
User Interface
	Region	Chart

Item

Identification
	Sequence	40
	Name	P1063_NLS_NUMERIC_CHARACTER_G
	Display As	Hidden
User Interface
	Region	Chart

Item

Identification
	Sequence	50
	Name	P1063_NLS_NUMERIC_CHARACTER_D
	Display As	Hidden
User Interface
	Region	Chart

Item

Identification
	Sequence	30
	Name	P1063_LANG_AVERAGE_SAL
	Display As	Hidden
User Interface
	Region	Chart

Process

Name
	Button Name	set_page_items
	Type	PL/SQL anonymous block
Process Point
	Sequence	10
	Process Point	On Load - Before Header
	Run Process	Once Per Page Visit (default)
Source
	Process	if :P1063_FSP_LANGUAGE_PREFERENCE is null then :P1063_FSP_LANGUAGE_PREFERENCE := 'en'; end if; if :P1063_FSP_LANGUAGE_PREFERENCE = 'nl' then :P1063_NLS_DATE_LANGUAGE := 'Dutch'; :P1063_NLS_NUMERIC_CHARACTER_G := '.'; :P1063_NLS_NUMERIC_CHARACTER_D := '\,'; :P1063_LANG_AVERAGE_SAL := 'Gemiddeld salaris'; else :P1063_NLS_DATE_LANGUAGE := 'English'; :P1063_NLS_NUMERIC_CHARACTER_G := '\,'; :P1063_NLS_NUMERIC_CHARACTER_D := '.'; :P1063_LANG_AVERAGE_SAL := 'Average Salary'; end if;

Region

Identification
	Sequence	10
	Title	Chart
	Type	Chart
Source
	Source Type	NATIVE_JET_CHART
	Region Source	select null as link , to_char(t.hiredate,'fmDD Month YYYY','NLS_DATE_LANGUAGE='||v('P1063_NLS_DATE_LANGUAGE')) as label , avg(t.sal) as "&P1063_LANG_AVERAGE_SAL. " from emp t group by t.hiredate order by t.hiredate
Chart Series
	Series Name	Series 1
	Series Type	Line
	Sequence	10